CHAPTER 4

ECOLOGICAL AND GEOGRAPHICAL OUTLINE OF THE ENTOMOFAUNA OF THE KURIL ARCHIPELAGO

SECTION 2. THE ECOLOGICAL-GEOGRAPHICAL FEATURES OF THE ENTOMOFAUNA OF THE KURIL ISLANDS

The natural conditions of the Kuril archipelago are reflected to a considerable degree in the entomofauna and determine its ecological-geographical features. Some of these features are typical in general for island faunas, in particular for the entomofauna of Sakhalin and Japan.

The habitation conditions of insects on the Kurils, despite the common features of the marine climate, turn out to be highly diverse. This is expressed in the existence of diverse ecological niches, which here have an exceptionally wide range, from mountain tundras to thermophilous broadleaved forests. The character of the entomofauna in various parts of the archipelago, on individual islands, and on specific sections of each island depends on climatic (general and particular, i.e., microclimatic), geographical (latitude of the locale and relief), edaphic, biocenotic, trophic, and historical conditions. The climate in combination with other geographic factors is of key significance in the distribution of the entomofauna over the Kuril Range.

The entomofauna of the southern islands, especially the southern region of Kunashir, where representatives of the fauna of the thermophilous broadleaved forests of the Japanese type are encountered in fairly large numbers along with boreal palaearcts and Okhotsk taiga species, is richest. As one moves northward, in addition to the disappearance of the broadleaved and coniferous forests (beginning with Urup), a marked impoverishment of the entomofauna is observed due to the dropping out not only of the majority of southern, but of many taiga species as well. The impoverishment reaches its extreme limit at the stretch between Simushir and Onekotan (Table 16). Many groups of insects in general do not reach the central islands. These include all the orthopteroid insects, many families of beetles (Scarabaeidae, Lucanidae, Lycidae, Buprestidae, etc.), bugs (Reduviidae, Aradidae, Lygaeidae, Acanthosomatidae, Pentatomidae), butterflies (Papilionidae, Nymphalidae, Satyridae, Lycaenidae, Hesperiidae), etc. (see Table 1). In the north of the range, on the islands of Paramushir and Shumshu, the composition of the entomofauna is somewhat richer than on the central islands; here the majority of southern species are also absent, but Kamchatka species which supplant them appear; these, however, are far from compensating for the species diversity which is characteristic for the southern islands (Table 1).

A similar pattern in the distribution of insects takes place on Sakhalin as well, where southern elements are distributed in the southern third of the island, mainly in the southwest (Kril'onskiy Peninsula) and along the west coast, approximately up to Uglegorsk (4940 N). Taiga-boreal groupings predominate in the north and east of the island.

The impoverishment of the fauna in the central and northern regions of the Kuril Range has been observed not only in the insects, but also in other animals, namely mammals, birds, reptiles, amphibians, and even in marine fauna (Klumov, 1963; Kusakin, 1970). Marine isolation, which prevents the free penetration of insects, especially those which fly poorly, into neighboring islands, is also of no little significance in the distribution of entomofauna over the archipelago.

The insects are also distributed unevenly within the limits of the southern region of the range. As already noted, the maximal number of species is concentrated on Kunashir; this is hardly surprising. Kunashir occupies the most favorable geographic position in the archipelago: it is situated further south of the other islands; its southern portion is protected from the west by the Siretoko Peninsula (Hokkaido) which extends to the north; the southern, western, and northern littorals are bathed by waters of the warm Soya Current; and the eastern shores of Kunashir are defended by the Lesser Kuril Range from the cold Oyashio Current which approaches from the north (Figure 29). All of this has created favorable conditions for the flourishing on Kunashir of a southern thermophilous flora, and for the existence here of a highly diverse entomofauna, frequently represented by southern forms.

The influence of the warm Soya Current, which bathes the southern and western shores of Iturup, is also felt significantly on the natural conditions of the southern region and the Okhotsk littoral of this island, where coniferous and coniferous-broadleaved forests flourish and where southern representatives of the entomofauna are concentrated. But on the eastern littoral of Iturup and Shikotan, the action of the cold current is already appreciably felt. Its branches, which run into the Vries and Boussole Straits, form a temperature barrier between the southern and central islands of the Greater Kuril Range. Currents of cold water, on the other hand, which circulate in the northern part of the Sea of Okhotsk and which bathe the western shores of the Central Kuril Islands (precisely in the stretch between Simushir and Onekotan), here create in the summer the worst climatic conditions on the archipelago; this is apparently in fact the cause of the marked impoverishment of the entomofauna in this region. Consequently, the local influence on the climate of warm and cold marine currents to a substantial degree determines the distribution over the territory of the southern islands of biological complexes, including the entomofauna.

We do not have at our disposal absolute data on the number of species in the various groups of insects on each individual island. Nevertheless, a certain pattern does emerge from the analysis of the most completely studied groups, according to which the maximal number of species live on Kunashir, somewhat fewer on Iturup, and even fewer or equal to the latter on Shikotan (Table 17). However, in a number of groups (leafhoppers and cicadas, hemipterans, some families of beetles, namely carrion beetles and leaf-beetles, the crane flies, etc.), this pattern is violated, and the number of species recorded on Shikotan proves to be greater than on Iturup. It is entirely probable that this seeming contradiction has risen as a result of insufficient study of the enumerated groups on Iturup.¹
 

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¹ In recent years many Soviet entomologists have collected insects mainly on Kunashir and Shikotan, and have substantially supplemented the information regarding the entomofauna of these islands in particular.

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Another common pattern has also been observed in the distribution of insects over the territory of the large islands: an appreciable impoverishment of the entomofauna on the eastern littoral as compared with the western and central areas remote from the ocean shore. We have already partially touched on this question in the review of the individual groups of insects (see Chapter 3). This is especially striking on Kunashir and Iturup, but it does occur on Paramushir and other large islands. For example, many thermophilous species, which are common on the west coast of Kunashir (the cicada Tibicen bihamatus Motsch., the cricket Pteronemobius fascipes nigrofasciatus Mats., the mole cricket Gryllotalpa africana Palis, the wingless long-horned grasshopper Diestrammena japonica Karny, the locust Parapodisma mikado Bol., the bug Carbula humerigera Uhl., many species of beetles of various families, many butterflies, including the Artemis saturnid moth [??] Actias artemis Brem., Mimeusemia persimilis Bil., Cystidia stratonice Cr., and a number of others), are not encountered on its east coast. The Japanese bark beetle species Polygraphus ssiori Niiji., such species of long-horned beetles as Cyrtoclytus caproides Bat., Paraclytus excultus Bat., Acanthocinus stillatus Bat., Eutetrapha chrysargyrea Bat., cockchafers Anomala lucens Ball. and A. rufocuprea Motsch., locusts Chorthippus biguttulus maritimus Mistsh. and Ch. kurilensis kurilensis B.-Bien., the Maack's swallowtail [??] Papilio maackii Mn., and some others, which are absent on the east coast, are not a rarity on the west coast of Iturup.

A similar phenomenon was also traced in the distribution of vegetation. Thus, the oak, sen, cherry, elm, and some other broadleaved species do not grow on the eastern littoral of the southern islands. They begin to be encountered at a considerable distance from the ocean shore, in the depth of the islands, and develop well along the Okhotsk littoral. O. G. Kusakin (1970) identified a similar pattern in the distribution of the Isopoda and Gastropoda fauna of the Pacific Ocean and Okhotsk littorals of the shores of the Southern Kurils. Such is the suppressant effect of the cold Kuril Current, and it is all the stronger the closer the current approaches the shores. How much the weather conditions differ on the opposite shores was shown in a consideration of the archipelago's climate (see Table 15). The cause of such a distribution of the entomofauna over the territory of Sakhalin also evidently lies in the disposition of warm and cold marine currents bathing the shores of Sakhalin (Figure 29).

Besides the general difference between the climatic conditions on the east and west coasts, the existence of various climatic microregions with a warmer or colder microclimate is characteristic for the Kuril Islands. In their turn, numerous sections, adjacent to one another, with markedly different microclimates, and accordingly with different groupings of insects, exist within such microregions. Let us consider as an example the biotopes of the caldera of Golovnin Volcano on Kunashir and the entomological microcomplexes inhabiting them.

The caldera of Golovnin Volcano is an extensive depression of irregular form, reaching 4.0-4.5 km in cross-section. Its northern portion is occupied by Lake Goryacheye, extending from east to west, connected with the Sea of Okhotsk by a narrow small river. Judging by the lacustrine terraces, the water level in the lake has been dropping gradually. The relief of the southern and eastern parts of the caldera is even. There are two small (height 130 m) secondary volcanic domes on the southern shore of Lake Goryacheye, almost in the center of the caldera. Both domes are relatively young, and have lateral calderas situated on opposite slopes. At the base of both craters there are solfataras which emit fumes of sulfurous gases. A small (230 m in diameter) crater lake named Kipyashcheye, is situated at the foot of the eastern dome. Its shores, which are entirely devoid of vegetation, are covered by discharges of volcanic ash and a hot loose layer of volcanic rocks. The water in the lake is hot, saturated with crystals of native sulfur, and therefore appears milky-white. This small lake has an outflow into Lake Goryacheye in the form of a narrow stream. The water in Lake Goryacheye is acidic, transparent, and cool over a large part of the surface; it is warm only in places, at the inflow of the stream flowing from Lake Kipyashcheye, and along the northern shore, where small jets of hot gases and fumes escape. The volcano's thermal activity is also manifested on the north and northeast shores of Lake Goryacheye. Here there are solfataras emitting, in addition to sulfurous gases, columns of aqueous vapors, small mud geysers, which also emit sulfurous gases, and areas with warm and hot ground surface. The bottom of the depression lies 350 m lower than the summit of the caldera. The outer slopes of Golovnin Volcano are covered with a fully stocked and relatively high coniferous-broadleaved forest.

Special climatic conditions are created in the caldera, protected on all sides from the wind, by virtue of the enumerated particular features of the relief and thermal activity of the volcano. Stagnation of cold air at the bottom of the depression does not take place here due to the large areas of hot ground, by contrast with similar relief forms in nonvolcanic regions. At the same time, the constant presence of the vapors of sulfurous gases in the air and soil adversely affect plants and animals: only organisms which are indifferent to these toxic gases survive and thrive in the caldera. Therefore, the distribution of vegetation thriving here is uneven.

The inner slopes of the caldera are almost everywhere covered by thick growths of Kuril bamboo which also forms the cover under the canopy of a mixed forest. The forest vegetation, by contrast with the outer slope of the volcano, is more sparse and appreciably impoverished. On the western and northern slopes it is better developed and is represented by a coniferous-broadleaved forest consisting of oak, Sakhalin cork tree, Erman's birch, maples, trichocarpous toxicodendron, panicled hydrangea, spruce, fir, and Japanese stone pine. The last of these grows at various heights from the summit of the caldera to its bottom, and even in direct proximity to solfataras. The narrow band of the western, northern, and partially the southern, shores of Lake Goryacheye is occupied mainly by "Maksimovich" alder and by willows, which frequently come very near the water. The "white-trunked elm-leaved birch" (Betula ulmifolia), which forms pure stands in limited areas, is encountered here and there. Groups of Japanese stone pine trees are found alternating with leafed trees along the entire shore.

In connection with the fact that the soil on nearly all of the shores of the lake is permeated with toxic vapors of sulfurous gases, the grass swards do not achieve normal development here. Only meager cereal-sedge associations and stunted small bushes of Sakhalin knotweed, fireweed, and some other plants can be seen under the canopy of the shoreline forest and on the open areas of the northeastern, eastern, and southern parts of the caldera. The crowberry (Empetrum sibiricum) grows in small patches in proximity to them. Bare places entirely devoid of vegetation, and small sandy areas are sometimes encountered. Herbaceous vegetation takes on a normal appearance only in moist sites, remote from solfataras, on the northwest shore close to the outlet of the river from Lake Goryacheye. The western terminus of the lake is overgrown with a reed (Phragmites communis) which runs down quite far into the water (Figure 30). A strip of dark coniferous forest, which is in a fairly depressed state, has extended like a small ribbon along the southern wall of the caldera.

Among the biotopes existing within the caldera, the following can be distinguished in accordance with the character of the entomofauna: 1) mixed coniferous-broadleaved forests of the inner slopes; 2) shoreline woody stands at the bottom of the depression; 3) bamboo growths; 4) associations of Japanese stone pine with ledum; 5) near-fumarole areas with warm soil; 6) sandy areas on the eastern shore of Lake Goryacheye; 7) the basin of Lake Goryacheye (Figure 31).

The entomofauna of the mixed coniferous-broadleaved forests of the inner slopes of the caldera comprises an impoverished variant of the entomofauna of the outer slopes. This is explained by the absence in the stands on the inner slopes of a number of broadleaved species which do not enter the caldera, and the absence of tall herbaceous vegetation (on the flowers of which many insects feed), namely the angelica, the goatsbeard, the meadow salsify, etc., which has been driven out of this site by the Kuril bamboo and possibly by the repellent action of the toxic gases. In the caldera, for example, there are no cicadas (Tibicen bihamatus Motsch.), many species of long-horned beetles, click-beetles, and other insects which are common in this region beyond its borders. Only the hymenopterans and flies remain relatively numerous here.

The complex of insects is more diverse in the shoreline stands at the bottom of the caldera. Groupings associated with alder, willow, birch, Japanese stone pine, and herbaceous vegetation are distinguished here. Thus, the leaf-beetle Basilepta balyi kurilensis L. Medv., the geometer Geometra papilionaria subrigua Prout., the long-horned beetles Plectrura metallica Bat. and Exocentrus testudineus Matsush., bark weevils Acicnemis palliata Pasc. and Acicnemis sp., bark-beetles Alniphagus alni Niiji., Xyleborus saxeseni Ratz., Scolytoplatypus daimio Blandf., and Cryphalus alni Krivol. live on alder; the last of these is found within the limits of the archipelago only on the shore of Lake Goryacheye. The "willow" aphid (Aphis furcula Zett.) and the poplar borer (Cryptorrhyncidius lapathi L.), which is in general very rare on the Kurils, form large colonies on the willow; several species of click-beetles (Anostirus daimio Lew., Ectinus piloselloides Schw., E. candezei Lew., Elater sanguinolenthus Schrnk., Ampedus pomorum Hbst.) are also encountered constantly. The caterpillars of the Artemis saturnid moth [??] (Actias artemis Brem.), aphids, namely the "birch Glyphina" [??] (Glyphina betulae Kalt.) and Symydobius oblongus Heyd., develop on birch (the last-named forms very large colonies frequented by ants), the "leaf-roller weevil [???rhynchites]" (Apoderus jekeli Roel.), and some others. The "giant conifer aphid" (Cinara pinahabitans Mordv.) is common on the Japanese stone pine, and is not noted in other places on the Kuril Range.

A fairly large complex of insects living in the near-shore stands is associated with herbaceous vegetation, mainly with tall herbaceous vegetation. This includes several species of leafhoppers (Lepyronia coleoptrata L., Ischidella albomarginata Sign., Philaenus spumarius L.), the long-horned grasshopper Metrioptera japonica Bol., the locusts Eirenephilus longipennis Shir., craneflies (Hylobius gebleri Boh., H. perforatus Roel., Lixus fasciculatus Germ., Larinus formosus Petri., Trichalophus albonotatus Motsch.), the leafroller Euops polita Roel., and the click-beetle Dolopius marginatus L., which live on the Sakhalin knotweed, a number of species of butterflies, among which geometers (Cidaria abraxina Btl., C. albostrigaria Brm., C. albicillata casta Btl., Iodis dentifasciata Warr.) and pearl butterflies (Argynnis ino Rott., A. aglaja chishimensis Mats.) predominate. In addition to the principal inhabitants, insects from other biotopes also fly here. For example, butterflies (the Gaschkewisch satyr - Neope gaschkewischi Mn.), which is associated with the Kuril bamboo, form mass clusters on willow trunks damaged by the poplar borer, where they feed on sap flowing out of the larval galleries of the beetle (Figure 32). This is the biotope most populated by insects in the Golovnin caldera. But, by comparison with the floodplain forests beyond the limits of the caldera, its entomofauna is also impoverished, despite a fair degree of diversity.

The grouping of insects associated with the Kuril bamboo is here represented only by some of the species which are generally characteristic for the Kunashir bamboo stands: butterflies, namely the "diana satyr" [??] (Lethe diana Btl.), the Gaschkewisch satyr (Neope gaschkewischi Mn.), and the "variegated skipper [??] (Halpe varia Murr.), and the "Japanese soldier-beetle/leather-winged beetle" [??] (Trypherus niponicus Lew.). The latter, although it does live on the Kuril bamboo, has been found only on the near-fumarole areas.

A small group of insects, consisting of only two species, the geometer (Arichana melanaria L. subsp.) and the small bug (Kleidocerys resedae Panz.), is restricted to Japanese stone pine groves which also contain the ledum (Ledum palustre), a distinctive plant association flourishing on a limited area at the foot of the eastern volcanic cone in the center of the caldera. This area, located close to Lake Kipyashcheye, is within range of the constant impact of sulfurous gases, which evidently do not affect the components of this microbiocenosis.

By contrast with other coniferous species, the Japanese stone pine is, overall, evidently highly resistant to the action of sulfurous gases, since it grows in direct proximity to hot sulfurous springs and solfataras in the Golovnin caldera and at other sites. Only the saplings on which the streams of gases and vapor fall constantly experience depression, gradually yellow and dry out. Such weakened small trunks and individual small branches are occupied by bark-beetles (Cryphalus piceus Egg., Pityophthorus lichtensteini Ratz.). Other insects are not present on Japanese stone pine at these sites.

The entomofauna of the near-fumarole areas, which are found at several sites along the shores of Lake Goryacheye, is of special interest. We regard as near-fumarole not only areas surrounding solfataras and hot springs, but also areas with warm or even hot soil impregnated by products of volcanic activity, not infrequently at some considerable distance from solfataras. Precisely such areas are encountered along the entire north shore (sometimes under the canopy of the near-shore forest), and occupy the eastern and southeastern shores of the lake. The ecological situation at various sites of this biotope is varied; this is indicated by the varied character of the vegetation and by differences in the groupings of insects. Nearly all near-fumarole areas are occupied by the ants. Three species of ants, Formica truncorum Fabr., Camponotus obscuripes Mayr., and Myrmica ruginodis Hyl., are encountered in the caldera; of these the first is the most numerous. According to the testimony of N. N. Konakov (1956), in 1946 there were many large anthills of Formica truncorum Fabr. in the caldera, composed of dry stump sprouts of ledum and bamboo; some of these had been dug up by bears. We did not find large above-ground ant colonies. According to our observations, the majority of the colonies are built in the ground. Such a dense settlement of ants was encountered nowhere on the Kuril Range.

In addition to ants, small crickets (Pteronemobius fascipes nigrofasciatus Mats.) which belong to a southern, namely Sino-Japanese species, live in areas of warm soil under the canopy of the near-shore forest in relatively thick but fairly short grass. Apparently, special microclimatic conditions, which are distinguished by elevated temperature and humidity, are created in this microbiotope, since the largest number of individuals are concentrated where the grass stand is thicker. These crickets do not go out into open areas. On the other hand, the leafhoppers Lepyronia batrachoides Hpt. and Philaenus spumarius L. keep to those very areas. The microclimate is quite different on the open spaces of the eastern shore of Lake Goryacheye, which are nearly devoid of woody vegetation and abundant in bare spots (Figure 33). It is characterized by lower humidity, greater solar radiation, and better ventilation. Here it is inhabited by its own microcomplex of insects, the basic components of which are the tiger beetle (Cicindela sachalinensis A. Mor.), a ground-beetle (Parena piceola Chd.), the click-beetle (Paracardiophoruspullatus Cand.), the "Japanese ground hopper/pygmy grasshopper" [??] (Tetrix japonica Bol.), a digger wasp (fam. Sphecidae), and the spring azure (Cyaniris argiolus ladonides d'Orza.), as well as ants. In addition to the constant inhabitants, insects from neighboring biotopes fly in as well, mainly butterflies: all species, trophically associated with the bamboo, a Eurasian swallowtail butterfly (Papilio machaon chishinana Mats.), a Bianor swallowtail [??] (Papilio bianor paradoxa Nakahara), the spirea pearl butterfly [??] (Argynnis ino tigroides Fruhst.), a nettle butterfly (Aglais urticae connexa Btl.), the spirea Neptis [??] (Neptis coenobita Stoll.), a cutworm moth (Bena prasinana L.), and a number of others.

All vegetation and insects are entirely lacking on the shores of Lake Kipyashcheye which are composed of loose volcanic rocks. However, N. N. Konakov (1956) discovered typhobiontic midges of the genus Discocerina Mcq. (fam. Ephydridae, the brine flies) in this section of the depression.

Patches of pure sand, residues of the past bottom of the lake, are occasionally encountered along the eastern shore of Lake Goryacheye among the near-fumarole areas. The larvae of the ant lion (Myrmeleon formicarius L.) and the large East Asian ground-beetle (Craspedonotus tibialis Schaum.) build trapping funnels in this sand. Their main quarry is evidently ants and some other small insects.

Lake Goryacheye itself, despite the content of sulfur compounds in the water, is also populated by insects. The entomofauna of the lake is not diverse from the species point of view. Larvae of caddis flies (Limnophilus rhombicus L. and Molanna angustata Curt.), larvae of a sialid fly (Stalis sibirica M. Lach.), larvae of the dragonfly (Enallagma deserti jezoensis Asahina), a Sigara (Arctocorisa) sp. bug, an aquatic beetle (Hydroporus sp.), and possibly other species live in it. In connection with the limited number of inhabitants and the attenuated competition, exceptionally favorable conditions are evidently created for some of them, and they multiply en masse. The Sigara bug, large swarms of which keep to the shallows along the shores, the caddis fly Molanna angustata Curt., and especially the sialid fly are among the mass species. During the flight of the latter (in the middle of July), the adult insects occupy the near-shore vegetation in enormous numbers; their egg deposits solidly cover the willow leaves hanging above the water, and even the trunks of the trees.

It can be seen from the above that groupings of insects inhabiting the caldera are differentiated with respect to several areas in accordance with their microclimatic conditions. On the whole, the entomofauna of the caldera, despite its general impoverishment, is distinguished by its originality; it is made up to a substantial degree by southern forms; some species are encountered only here; others are represented by a large number of individuals, whereas outside of the caldera they are encountered extremely rarely. The example of diversity of the microbiocenotic complexes in the caldera of Golovnin Volcano is not unique, but is extremely significant. One can also cite a fair number of examples of distinctive communities of insects which are grouped around fumaroles, solfataras, and hot springs, as will be discussed below. On the other hand, it is appropriate once again to emphasize here that the existence of distinctive climatic microregions associated with volcanic activity is a distinguishing feature of the Kuril archipelago.

But the formation of areas with different microclimates is not associated only with volcanic activity. The combination of mountain relief with the influence of the sea and vegetation plays a great role in this regard. Even the brief observations which we carried out in the region of Alekhino set. (Kunashir) demonstrated appreciable differences in microclimate along the littoral of the Sea of Okhotsk and in direct proximity to it, at the top of a small cone overgrown by forest. Within a period of 10 days (from July 6 through 16, 1962), we measured humidity and temperature of the near-soil layer of air at two sites: 1) on the wind-beaten northwest slope, facing the sea, covered with mixed herbaceous meadow vegetation and dwarf Kuril bamboo, and 2) at the top of the same cone under the canopy of a mixed broadleaved forest. The distance between the observation points was about 100 m. Weekly thermographs (M-16 w) and hygrographs (M-21 w) were used to measure temperature and humidity. Analysis of the data obtained showed that the relative humidity of the air was constantly higher on the first open area; it ranged over the course of a day from 100 to 40%, and on rainy days from 100 to 97%; it exhibited more abrupt gradients, as did the temperature. At the second site, under the forest canopy, the humidity of the air did not reach 100% even once (even on rainy days), and ranged from 88 to 37%; the gradients were less sharp; the temperature conditions were more even; the maximal fluctuations of temperature were 8.0-32.5 and 14-16 on rainy days. In the observation period, the temperature maximum and the relative humidity minimum at both sites fell at 3 p.m.

Thus, the microclimatic conditions of the seashores are not identical to the conditions not only of the deep inland regions of the islands, but even nearby mountain slopes facing away from the seashore. The distribution of the entomofauna depends to a substantial degree on the disposition of the various microclimatic areas. Insects associated with herbaceous vegetation (hymenopterans, leafhoppers, flies, butterflies, and beetles) usually keep to the coastal marine terraces occupied by forb meadows. Some dendrophilic species (particular species of long-horned beetles, sawflies, butterflies, etc.) appear in these biotopes periodically, more often in good weather, and are concentrated on the flowers of large plants of the carrot family, where they undergo supplementary feeding.

The distribution of insects along the vertical zones on the Kurils also has its own peculiarities which are different from those on the continent. We have already touched on this question in describing the character of the vegetation. Let us dwell on this in somewhat greater detail. Inversion phenomena, in the presence of which vegetation loses the clearly marked boundaries of vertical zones, occur under the conditions of a moist and cool marine climate, in which, as it were, the evening out of temperatures and humidity at various altitudes takes place. As a result, the dark coniferous species (spruce, fir, Japanese stone pine) and Erman's birch, which grow high in the mountains on the continent, descend into the valleys on the Kuril Islands and even to the seashore, where they grow in close proximity to broadleaved species. And the latter, conversely, ascend along the slopes, sometimes to fairly great altitude (up to 400 m above sea level). The insects, as they do not encounter palpable climatic barriers, also follow their food plants. Therefore, together with the valley species, many alpine butterflies (the leaf-roller Eurydoxa advena jezoensis Mats., geometers Garaeus mirandus Btl., Eustroma inexcricata Btl., Hemerophila subplagiata Wrk., cutworm moths Ochropleura stenzi Led., Agrotis patula Wlk., Anarta melanopa Thnb., Mythimna flavostigma Brem., Actinotia polyodon Cl., etc.), bark-beetles (Cryphalus kurenzovi Stark, Dryocoetes ussuriensis Egg., Pityogenes foveolatus Egg.), some species of ground beetles, and other insects inhabit the dark coniferous-broadleaved forests.

At the same time, the typical inhabitants of the valleys ascend the mountains and not infrequently reach the tops of volcanoes. This is especially striking on the southern islands, where the vertical vegetation zones are represented more completely. Many species from the Golovnin caldera (547 m above sea level), which we have just considered, may serve as an example. Ants, Camponotus herculeanus L. and Formica fusca L.,and the larvae of the locust, Parapodisma mikado Bol., have been found on the rocky peak of Mendeleev Volcano (895 above sea level), which is overgrown with dwarf small shrubs of "Maksimowich" alder, willow, spirea, and Japanese stone pine; larvae of a leafhopper (probably, Sinophora submacula Metc. et Hort.) have been found on willow shrubs; the weevil Phyllobius sp. has been found on alder; butterflies, namely the Eurasian swallowtail butterfly, the Bianor swallowtail [??], and the diana satyr [??], have also flown here from the lower zones. All these species are not alpine and are common at lower altitudes, in the coniferous-broadleaved forests. In the cup-shaped crater of Atsonupuri Volcano (1205 m above sea level), which is surrounded by an alpine tundra belt, the vegetation is almost the same as is found at the top of Mendeleev Volcano: mountain cranberry and crowberry are added to the procumbent "Maksimowich" alder and willow bushes. Of the insects, the following are encountered here: ants (Myrmica rubra L.), the "Sakhalin tiger beetle" [??] (Cicindela sachalinensis A. Mor.); on alder, the Eurasian swallowtail butterfly caterpillar and pupa and, in large numbers, a leaf-beetle (Cryptocephalus pumilo Suffr.) and a leafhopper (Oncopsis sardescens An.); and a small [??] leaf-roller, on willow. These insects are encountered in the same numbers at the foot of the volcano and near the sea. Having reached the peaks, they formed impoverished biocenotic complexes there, and cannot be regarded as accidental ecdemic forms. The discovery of larvae and the active behavior of the imagines, which is expressed in feeding, mating, and oviposition, indicate this. The discovery of Eurasian swallowtail butterfly caterpillars in different years (1961 and 1963) in the crater of Atsonupuri Volcano is highly significant.

But, along with active penetration and habitation in the high-mountain regions of a number of valley species, the simple sweeping up of various insects to the alpine tundra belts by strong rising air currents flows, from the elfin wood zone and from the zones of forest vegetation that cover the slopes and are located lower down, does occur. Thus, V. A. Nechaev observed the disorderly clustering of the most diverse insects at the top of Tyatya Volcano (1822 m above sea level) in the alpine tundra belt: a long-horned beetle (Leptura scotodes Bat.), ground-beetles (Lebidiaoctoguttata Mor.), click-beetles (Hypnoidus kurilensis Gur.), bugs (Acanthosoma spinicolle Jak., Elasmostethus interstinctus L.), hymenopterans (sawflies and parasitic wasps), and flies. The majority of these had already died; some were half-alive. N. N. Konakov (1956) also mentions similar clusterings of insects in the crater of Trezubets Volcano (1013 m above sea level) on Urup. Apparently this is a not infrequent phenomenon on the Kuril Range.

These examples suggest that the distribution of the entomofauna along vertical zones on the Kuril Islands is leveled out to a significant degree by comparison with continental regions, due to a certain uniformity of ecological conditions at different altitudes. The correctness of such an inference is confirmed by the peculiarity of the alpine fauna of Sikhot-Alin', which is capable of existing not only in mountains but in the valleys as well, in biotopes which are similar in ecological conditions, namely in sphagnum bogs and on seashores (Kurentsov, 1965a). It is significant that the ornithologist, V. A. Nechaev (1969), observed the same pattern of disturbance of vertical zonality in the distribution of birds along mountain slopes on the Southern Kurils, and I. M. Likharev (1957) cites the same regular pattern for terrestrial molluscs on the islands of Iturup and Shikotan.

Other factors, in particular soils, in addition to climatic factors, are also of no little significance in the distribution of particular groups of insects over the archipelago. The limited distribution over the Range of orthopterans, lamellicorns, and some other insects is probably explained precisely by the absence of suitable soil conditions for the development of the preimaginal phases.

It is generally known that vegetation is a powerful factor, on a par with climate, determining the appearance of the entomofauna of various regions. While depending on the climate, vegetation itself creates a multiplicity of microclimatic areas and microareas which serve as ecological niches for different insects. In addition, it is the source of nutrition for the majority of phytophage insects that are trophically linked to specific plants. Therefore, the presence at a given locale of particular species of insects is governed by the existence there of particular plants or groupings of them. The more complex the composition of plant formations, the more diverse the entomofauna populating them. This rule is entirely applicable to island entomofauna as well, the distribution of which over the Kuril archipelago is to a substantial degree linked with the distribution of vegetation. Nonspecialized predators, necrophages, and some other groups which possess a high degree of ecological plasticity are the only exception. They frequently have a wider distribution, since they find food in various biotopes independently of specific plants. Darkling beetles (Emypsara riederi Fald. and Phaleromela subhumeralis Mars.), a carrion beetle (Necrophorus vespilloides Hbst.), a horsefly (Tabanus montanus Myn.), a bumblebee (Bombus japonicus Fr. et Wag.), etc., which are widely distributed on the Range, may serve as examples of such insects on the islands.

In a number of instances, the discovery of some phytophage insects in locales where their principal food plants are lacking is explained by historical factors, and points to the existence in the past on this territory of plant associations with which the insects have been linked. Thus, the discovery on Urup of bark-beetles and long-horned beetles which typically live on spruce and fir (Polygraphus sachalinensis Egg., P. gracilis Niiji., P. poligraphus L., Cryphalus kurenzovi Stark; Judolia sexmaculata L.) points to the flourishing in the past on this island of dark-coniferous species. After their disappearance, the insects which were associated with them adapted to life on the Japanese stone pine. However, these species do not penetrate to the north of Urup; this is explained, on the one hand, by the same historical factors, and on the other, by the worsening of the climate. The role of the historical factor in the distribution of entomofauna over the archipelago is considered in detail in Chap. VI; therefore we will not linger over this question here at any length.

Let us dwell on some general ecological features of the Kuril insects which have been elaborated under the influence of island conditions of existence in the process of historical development. Remaining constantly in an atmosphere of high humidity, cool temperatures, and decreased solar radiation elicits in the organisms a respondent reaction and specific adaptations which are observed on the Kurils not only in insects but in other animals as well. The influence of the marine climate is reflected, first and foremost, in the ecological structure of the Kuril entomofauna. The overwhelming majority of the insects are represented here by mesophilic and hygromesophilic species which are encountered in all eco-areas. There are a fairly large number of hygrophilic species, but even on the islands they are restricted to especially moist conditions of existence, to the floodplain streams and rivers, the margins of lakes, bogs, and seashores. The xeromesophilic species which are localized in near-fumarole and relatively dry meadow areas, as well as in stony scree, constitute a very small proportion of these insects. Among these can be classified some leafhoppers (Kuvera flaviceps Mats., Paracercopis fusca Mel., Diplocolenus ikumai Mats.), aphids (Aphis jacobaeae Schr., A. spiraephilae Patch., Myzus cerasi F., and species of the genus Dactynotus), isolated species of beetles (Cicindela sachalinensis A. Mor.), particular representatives of the xerophilic subgenera of craneflies of the genus Tipula (Lynatipula, Vestiplex, Odonatisca), and some others. True xerophils, on the other hand, are entirely lacking in the entomofauna of the Kuril Islands; there are not even xeromesophilic elements in many groupings of insects. The number of light-loving forms, the photophils, and especially the heliophils, is extremely limited. The nearly complete absence of borers (Buprestidae), typical heliophils, of which only 3 species (Agrilus ignoratus Obenb., Cratomerella psitaccina Heyd., C. proteus Saund.), encountered on the western shore, where there are more sunny days, were found on Kunashir and Iturup, may serve as a dramatic example demonstrating this feature of the Kuril entomofauna.

The climatic conditions of the summer season are especially important for insects in which active vital processes proceed in the warm time of the year. At the present time there is not sufficiently complete information regarding the radiation regime, temperature, and humidity of the air on the entire territory of the archipelago. However, it is known that it is precisely summer which is characterized by heightened humidity (the mean monthly relative humidity in July-August is 90-97%), low solar radiation due to the large number of days with fogs (reaching 26-28 per month at individual sites), and solid clouding (10-15 days a month). As a result, the duration of solar radiation in July is only 20-40% of that which is possible (Barabash, Lesevich, 1967). The weather conditions are somewhat better on the west coast of the large islands due to the factors already mentioned, and the duration of solar radiation is greater. Therefore, the majority of the photophils encountered on the islands are confined to the western littoral (some orthopterans, a cicada Tibicen bihamatus Motsch., a number of species of cockchafers and scarabaeid beetles, some diurnal butterflies, gold wasps, etc.).

The high humidity permits some aquatic animals to shift to a terrestrial existence, and others (the moisture-loving forms), to multiply in large numbers. For example, V. A. Nechaev found leaches on Kunashir on the surface of the soil far from the water; E. I. Shornikov (1969) describes a new family and a species of small shelled crayfish (Terrestricythere ivanovae) which is adapted to a terrestrial mode of life in the supralittoral, on Iturup; wood lice of the fam. Oniscoidea, openly crawling along the trunks of trees and some places forming large clusters, are encountered en masse in the coniferous-broadleaved forests of Kunashir; spittlebugs, whose larvae live in foamy secretions openly on shoots, leaves, and needles of plants (in a drier climate they usually hide in the axils of leaves), are very numerous in the Southern Kurils.

Adaptive changes in the Kuril insects which take place under the influence of specific island conditions of existence proceed in various directions. They are manifested both in some morphological and in biological features which are common to a number of groups. A change in the coloration in the direction of melanism, the loss of small scales, and partially, of the fine hairs on the elytra by some beetles and the acquisition of glossiness of the integuments are classified as morphological adaptations. Many forms that live on the islands are distinguished by a darker coloration, and on the basis of this character have been described as independent species, subspecies, or geographical races. Examples of such forms occur among various groups of insects. The East Asian cricket, Pteronemobius fascipes, in the island portion of its range (on the Kurils and in Japan) is represented by a darker form, set apart as the subspecies P. fascipes nigrofasciatus Mats. Another cricket, P. nitidus yezoensis Shir., is also distinguished from the typical form, distributed on the continent, by dark coloration (Bei-Bienko, 1966). Among the cutworm moths (Noctuidae, Lepidoptera), some widely distributed species form island subspecies on the Kuril archipelago and partially in Japan which are characterized by dark coloration: Agrotis exclamationis informis Leech., Euxoa islandica karschi Gr., Mythimna flavostigma Brem., Parastichtis funerea oriens Warr., etc. There are such subspecies among other lepidopterans as well; in particular, the swallowtail Parnassius stubbendorfi Mn. is represented on Sakhalin and the Southern Kurils by two close subspecies which have darker wings (Kurentsov, 1970). The subspecies Papilio maackii kurilensis Mats., which is predominant on Kunashir, is distinguished from forms living on the continent by distinctly darker wings, as is the case for the blue Lycaena euphemus ogumae Mats. and the Kuril subspecies of the "Siberian silkworm" [??], Dendrolimus superans albolineatus Mats. A. I. Kurentsov (1970) observes darkening of the forewings, the presence on them of larger black spots, and marked shortening of the red marginal fascia [??] on the hindwings in the island subspecies of the small copper, Chrysophanus phlaeas daimio Seitz. (Lycaenidae - the blues).

A tendency toward darkening of coloration, loss of scales on the elytra, and the appearance of glossy integuments has been observed simultaneously in some beetles. This phenomenon has been noted in bark-beetles (Krivolutskaya, 1958, 1969, 1970) in the genera Cryphalus, Dryocoetes, Polygraphus, and Ips, and in long-horned beetles in the genus Monochamus. It consists in the fact that in genera for which a thick covering of the elytra by densely adjacent scales is characteristic, species devoid of this covering are encountered only on the islands (Polygraphus ssiori Niiji., Cryphalus alni Krivol.). In addition to the loss of scales, in Polygraphus ssiori Niiji. the elytra have a smooth shiny surface, as in species of the genus Blastophagus; this distinguishes it from all other representatives of this genus. Sometimes only specific parts of the elytra become glossily shiny, for example, the declivity in the Japanese form of the spruce bark-beetle (Ips typographus f. japonicus Niiji.). In the latter case, the formation of an ecotype evidently takes place, since this form is encountered in Japan, on the Kuril Islands, Sakhalin, and in the coastal Tugurskiy Rayon of Khabarovskiy Kray, and was recently found in the high-mountain regions of the Ukrainian Carpathians (Pogorilyak, 1968), i.e., in regions with a cool moist climate. But, this character becomes less prominent and may completely disappear even on Sakhalin in populations of the spruce bark-beetle which live in sites far from the sea with a drier microclimate, in the Tym'-Poronaiskaya valley. A gamut of transitions from the lusterless declivity of the elytra, which is characteristic for the typical spruce bark-beetle, to a glossily shining declivity, is encountered there. On the continent, apart from coastal and mountainous regions with moist climate, this character is never manifested in the spruce bark-beetle (Krivolutskaya, 1958). The same glossiness of the elytra is exhibited by Monochamus nitens Bat., the Japanese species found in the south of Kunashir, in which the hairy integument is reduced only to patches of white hairs which form a spotty pattern, sharply contrasting with the black remaining surface of the elytra which shines like lacquer. In other species of the genus Monochamus, more or less thick hairs cover nearly the entire surface of the elytra, especially in the rear.

The biological mechanism of the formation of the morphological changes in question is thus far not entirely clear. It must be assumed that it is associated with the complex of specific climatic conditions of the islands under which cool temperatures, high air humidity, and low solar radiation simultaneously influence the insects. It is necessary to carry out special investigations in order to decipher the causes of such adaptive changes. But it is known that dark-colored forms predominate among insects living under the conditions of a cool and fairly moist climate (in alpine and Arctic regions) (Yakhontov, 1964). Some insects that have been raised at lowered temperatures (for example, the turnip moth Agrotis segetum Schiff.) also produce dark-colored forms (Kozhanchikov, 1940).

The ground-beetles of the island subgenus Damaster of the genus Carabus may serve as an example of other morphological adaptations induced by alimentary characteristics. They have long walking legs and a narrow, markedly elongated pronotum (Figure 34). Having adapted to feeding on marine and dry-land molluscs, these ground-beetles are very numerous in the dark coniferous-broadleaved forests of the South Kurils and keep to seashores and broadleaved forests. Despite their long legs, they are not distinguished by the capacity to run rapidly, as are other ground-beetles which have to pursue fleeing prey, but evidently are easily able to climb on the shells of molluscs and even turn them over when necessary. The narrow and long pronotum facilitates deep penetration into coiled shells and devouring of their contents.

The darkling beetle Emypsara riederi Fald., which lives on sandy seashores and possesses the capacity to dig completely into the sand, has a variegated protective coloration which is not typical for its family, and a markedly convex, nearly hemispheric body (Figure 35). The former adaptation provides for its protection against predators, the latter eliminates the danger of being crushed under the weight of sand; at the same time sand is readily shed from the convex body when the beetle emerges onto the surface.

A fly of the fam. Coelopidae, which lives among the rotting layers of sea cabbage (Laminaria) thrown onto the shore in the tidal zone on Urup, is covered with numerous long spine-like setae (Figure 36) that undoubtedly have an adaptive character. The setae protect the body integuments from soiling by the mucus of the rotting algae. These examples of morphological adaptations must be regarded as morphological types. They attest to the high degree of adaptation of the insects to living in specific ecological niches.

We classify phenological features which are characteristic for the Kuril entomofauna and the changes in the behavior of some insects as biological adaptations. The phenological adaptations are expressed in a shift in the periods of development in the overwhelming majority of insects from spring toward the summer by approximately a month as compared with continental regions of the Far East; this is governed by the late, protracted, cold spring. As we do not have sufficient information at our disposal regarding all phases of development of the insects, we can only make judgments regarding the periods of flight of particular species for which there exists the corresponding comparative data in the literature (Kurentsov, 1939, 1970; Krivolutskaya, 1965b; Petrenko, 1965) for the continental regions of Siberia and the Far East (Table 18). In the main, species which are either mass or numerous for the Kuril Islands, that were collected in large numbers, were used as examples. It can be seen from Table 18 that the flight periods of these species on the archipelago are later and more compressed as compared with the continent.

As has already been mentioned above (see Chapter IV, section 1), the appearance of the same phases of development in the very same species of insects and plants commences at different times on the eastern and western littorals, even within the limits of the same island. True, this takes place on the large islands, Kunashir and Iturup, where the Okhotsk and Pacific Ocean coasts are separated from one another by a distance of 10-30 km. Thus, on the Okhotsk coast of Kunashir, many species of butterflies, beetles, and other insects begin to fly 10-12 days earlier than on the Pacific Ocean coast. A similar pattern is also observed in the flowering of plants.

An interesting feature of the life cycle of some Kuril leaf-rollers (Lepidoptera, Tortricidae) was discovered by V. I. Kuznetsov (1968b). It was found that a delay in development ensues in some leaf-rollers, i.e., a summer diapause, in the unfavorable period of constant fogs and rains, which lasts approximately from the middle of June to the beginning of August. Various species enter diapause in different phases of the development: Acleris hispidana Chr. and Epinotia salicicolama Vl. Kuzn. in the pronymph phase, E. rasdolnyana Chr. and Zeiraphera subcorticana Shell. in the pupal phase. This feature enables the leaf-rollers to live through the unfavorable period in the resting state, like insects of arid regions, which enter diapause in the driest and hottest season of the year. Diapause ends in the leaf-rollers with the onset of drier and sunnier weather. Such a feature in the developmental cycle was elaborated in the organisms in the process of development in response to habitation under monsoon climate conditions. It is entirely probable that it is also characteristic of other insects living on the islands.

It is apparently not accidental that the time of the mass flight of the majority of insects on the archipelago falls in the second half of July-August. Apart from other factors, the sum of the effective temperatures which by this time reaches a fairly high value, and the fact that August is the warmest month on the islands (Vitvitskiy, 1954) are evidently of fundamental significance in this respect. In Primorskiy Kray, the flight of many southern species (Dermoleipa juno Dalm., Antheraea yamamai ussuriensis Shachb., Adris tyrannus Guen., Rhodinia jankowskii Oberth., Rh. fugax diana Oberth., etc.) also takes place at the end of the summer-beginning of autumn, when the sum of the effective temperatures reaches a specific value necessary for completion of the developmental cycle. It is known that the number of generations in the course of a year in different species of insects is determined mainly by the sum of the effective temperatures, which differs in different climatic zones (Dobrovol'skiy, 1969). A Japanese saturnid moth [??] (Dictyoploca japonica Btl.), a leaf-roller (Eurydoxa advena Fil.), a bug (Dinorhynchus dybowskii Jak.), long-horned beetles (Dihammus fraudator Bat. and Eryssamena tuberculata Pic), and some others are classified as late flying species on the Kurils.

Under the influence of increased air humidity and decreased solar radiation, the behavior of some crepuscular insects, in particular butterflies, changes. We have repeatedly had occasion to see two species of butterflies (Mimeusemia persimilis Btl. and Cystidia stratonice Cr.) actively flying and feeding on flowers in the daytime in the presence of sunlight in the dark coniferous-broadleaved forests on the southwest coast of Kunashir, whereas on the continent they appear only at twilight (Figure 37). A cicada, Tibicen bihamatus Motsch. (Figure 38), is also distinguished by singular behavior under Kuril Islands conditions. It usually keeps to the underbrush, much more rarely ascends to the crowns of high trees, and is readily picked up, so that there is no great difficulty in collecting a large series of these cicadas even on a hot sunny day. On the continent and even in Japan (on Honshu), the large cicadas are generally found high in the crowns of trees; therefore, it is usually very difficult to catch them. The reason for such behavior in this cicada has not been figured out; it evidently resides in the features of the microclimate of the Kuril broadleaved forests.

Yet another feature of the Kuril entomofauna consists in the fact that a number of species of insects multiply en masse on some islands, while on others they are encountered singly. This phenomenon may be regarded as a regularly occurring one, since it has been followed in the most varied groups of insects; nevertheless, it is thus far difficult to explain. We have already touched on this question when considering particular groups of insects. At this point, let us confine ourselves only to several examples: the leaf-beetle, Clitena fuscipennis Jac., multiplies en masse on Iturup, is encountered singly on Kunashir, and is not found on the other islands; another leaf-beetle, Basilepta balyi kurilensis L. Medv., is encountered en masse on Kunashir, singly on Shikotan, and has not been found at other sites; long-horned beetles Allosterna tabacicolor bivittis Motsch., Strangalia aethiops Poda, and Leptura scotodes Bat. are extremely numerous on Iturup and Kunashir, but are rare on Shikotan and the other islands; the mass multiplication of the "bamboo" aphid [??], Takecallis bambusae Mats., has been observed only on Urup, while that of the "bird cherry" aphid, Rhopalosiphum padi L., has only been observed on Iturup; butterflies that are associated with the Kuril bamboo, Neope gaschkewischi Mn. and Lethe diana Btl., achieve high numbers only on Kunashir, whereas thicker growths of Kuril bamboo are found on Iturup and Urup. According to the data of N. A. Violovich (1956a, 1968), a horsefly (Chrysozona tristis Big.) is very numerous in the south of Kunashir and Yuriy, is encountered singly on Zelenyy under the same weather and other conditions, while Hybomitra montana montana Meigen, to the contrary, is common on Zelenyy but is not found on Yuriy. According to our observations, the distribution of black flies (Simuliidae) is extremely uneven on the Kuril Range: on the majority of the islands, despite the presence of suitable sites for development, there are practically no black flies or their number is extremely small. Urup, where there is an inestimable multiplicity of black flies, is an exception, although, it would seem, there are no more rivers and streams in which their larvae develop than on the other islands. There are black flies in local sections on Iturup as well, whereas they are completely absent on neighboring sections.

The landscape or background species of insects which are characteristic for the very same eco-areas, are different on different islands due to the above characteristic, as well as in connection with the uneven distribution of the entomofauna over the Kuril Range. Sometimes they are confined to specific parts of the single island, as occurs on the west coast of Kunashir and Iturup. More rarely identical landscape species are characteristic of two or three neighboring islands. Besides the landscape species, there are complexes of insects which are characteristic for specific plant formations and other biotopes and which are often not repeated on other islands; we will go on to consider these in section 3 of the present chapter.