Morphology. Caterpillars of older ages are very large, reaching 11 cm in length, usually black or black-silver with a wide silvery stripe along the back and a yellowish stripe on the sides. Behind the head are two bands of blue burning hairs, clearly visible in a disturbed caterpillar. The number of instars and the size of the head capsule vary depending on the duration of the caterpillar phase, which can take one, two or three calendar years. Usually male caterpillars have 5-8 instars, female caterpillars - from 6 to 9 instars.
The color of butterflies is highly variable, from dark brown to light yellow, almost white. Typical light gray and dark brown coloration with dark, almost black bands and washed out light spots along the margin on the forewings. The hindwings are usually uniformly brown. The wingspan of males varies from 40 to 83 mm, females - from 60 to 104 mm.
Eggs are oval, yellowish-brown, form loose clutches or chains on needles or branches of fodder plants. Pupa in dense cocoon impregnated with blue stinging hairs; placed on the branches, less often - on the trunk.
Forage breeds. The Siberian silkworm feeds on almost all species of the Pine family. Prefers Siberian fir, Siberian larch and Siberian cedar. The white-striped silkworm prefers Sakhalin fir, Ayan spruce and Kuril larch. On the Japanese islands The silkworm damages several species of fir and Korean pine.
Life cycle.
For the Siberian silkworm, a two-year development cycle is typical, taking three calendar years. Butterflies fly and lay their eggs in the last third of June - the first half of July. The average fecundity is about 300 eggs. The egg stage lasts 17-19 days. The caterpillar hibernates twice: in the second or third instar and in the fifth or seventh instar. They hibernate under the litter, curled up in a ring. Caterpillars that feed in the spring of the third calendar year cause maximum damage to trees. They pupate in late May - early June in the crown. The pupal stage takes about three weeks.
The onset of outbreaks of mass reproduction of the Siberian silkworm is usually associated with the transition of a part of the population to a one-year development cycle (taking two calendar years). As a result, butterflies of both generations appear simultaneously, which contributes to a significant increase in population density. At their peak, silkworm caterpillars are affected by viral, bacterial and fungal diseases. About 40 species of parasitic insects of eggs (Telenomus tetratomus Thoms., Ooencyrtus pinicola Mats.), caterpillars (Rogas dendrolimi Mats., etc.) and pupae (Masicera sphingivora R.D., etc.) also contribute to the decline in numbers.
Harmfulness assessment. The Siberian silkworm is the main pest of the coniferous forests of Asian Russia. Outbreaks of its mass reproduction are especially destructive in the dark coniferous taiga with dominance of fir and cedar. Only in the last 100 years in the territory Krasnoyarsk Territory 9 outbreaks of the pest were registered. As a result, over 10 million hectares of forests were damaged. The last outbreak of mass reproduction ended here in 1996. More than 140 thousand hectares of forest died, about 50 million cubic meters of timber were lost. Five years later, thanks to the attack on the weakened trees of the big black barbel, the area of withered forests doubled.
The Siberian silkworm (otherwise hemp) is a dangerous insect pest that damages more than 20 species of coniferous trees. The insect is especially disastrous for larch, fir, and cedar. Spruce and pine are much less often damaged by butterflies.
The Siberian silkworm belongs to quarantine species. Even if it is absent on the territory of the country, there is a real threat of its independent penetration or introduction from outside, which can lead to massive damage to plants and plant products. That is why it is strongly recommended to carry out phytosanitary measures: when exporting conifers, they must be disinfected or debarked.
An adult Siberian silkworm (photo) reaches 10 cm, females are larger than males. An insect on tree branches lays about 200 eggs (sometimes up to 800). The butterfly does not feed, but the larva that hatches after 2-3 weeks immediately begins to eat the needles, moving to the very top of the crown. With a lack of nutrition, the caterpillar of the Siberian silkworm can damage the bark of trees and young cones. In autumn, the caterpillars leave for the winter. In the spring, their active life activity resumes. Pests pass 6 - 8 ages.
At the end of the development cycle, the caterpillars weave a dense cocoon in which pupation takes place. Pupae grow for 3-4 weeks, at the end of June adults emerge from them and start mating.
As a rule, the Siberian silkworm is found in a healthy forest in small numbers. An outbreak of population size (mass reproduction of an insect) can lead to an ecological catastrophe. Drought is one of the main reasons for this phenomenon. During dry seasons, the caterpillar has time to develop not in two, but in one year. The population doubles, the natural enemies of the butterfly do not have time to hit a sufficient number of individuals. Butterflies freely reproduce and give offspring. Early spring fires are another cause of silkworm outbreaks. The fact is that silkworm caterpillars hibernate in the forest litter. Telenomus also lives there - the worst enemy that eats silkworm eggs.
And early spring fires destroy most of the telenomus population, which leads to the appearance of centers of mass distribution of the silkworm.
Beyond Telenomus natural enemy silkworm is a cuckoo, as well as a fungal infection.
The real sword of Damocles was the Siberian silkworm for coniferous plantations in Siberia and Far East, where its invasion, comparable to the locust invasion, destroyed more than one thousand hectares of coniferous forests, including young spruce and pine seedlings. Huge territories have turned into bare treeless spaces. According to some scientists, it will take about a hundred years to restore these forest plantations. According to others, the restoration of forest plantations after being damaged by a pest is impossible.
With the mass reproduction of the Siberian silkworm, it is very important to treat the plants with insecticides. Lepidocid is one of the most effective drugs. To prevent the spread of the butterfly, it is necessary to regularly inspect the plants and treat them with insect repellents.
© Grodnitsky D.L.
Siberian silkworm
and the fate of the fir taiga
D.L. Grodnitsky
Dmitry Lvovich Grodnitsky, Doctor of Biological Sciences,
head cafe natural disciplines Institute of advanced training of educators (Krasnoyarsk).
Who has not heard about the gluttony of locusts, which, during mass reproduction, unites in multi-million flocks, flies hundreds of kilometers in search of food and destroys crops of grain and cotton, orchards and vineyards in a matter of hours, and eats not only leaves, but also branches, and even bark from the trees? Many times, locusts doomed hundreds of thousands of people to starvation. Those who were lucky enough to survive the invasion erected monuments in honor of their salvation. However, the locust rages mainly in the tropics and subtropics, while for the Siberian forests, the mass reproduction of the less known, but no less voracious insect, the Siberian silkworm, becomes a real disaster ( Dendrolimus sibiricus). It was first described by S.S. Chetverikov more than a hundred years ago. Nowadays, the silkworm has ceased to be exclusively Siberian: the western border of its range has long passed the Urals and continues to slowly move through the European part of Russia.
The adult Siberian silkworm is a large butterfly up to 10 cm (usually four to seven) in wingspan; males are smaller than females. Butterflies do not feed (they do not even have a proboscis), but the caterpillars have an excellent appetite. They eat the crowns of all species of coniferous trees growing in Siberia, but most of all they prefer the needles of larch, fir and cedar, a little less - spruce, and even less pine. At the same time, the caterpillars behave rather strangely: for one to two weeks they actively feed and gain weight, after which an incomprehensible period of rest (diapause) occurs, when they hardly eat. By the way, caterpillars of another pest (also quite large) - gypsy moth ( Lymantria dispar) - feed continuously and completely complete development within a month and a half, but the life cycle of the Siberian silkworm usually stretches for two years. The biological meaning of a short-term diapause in summer, when everything seems to be favorable for the growth and development of the larva, is still unclear.
Ecological catastrophy?
The Siberian silkworm is a common inhabitant of forest ecosystems; in a healthy forest, it is constantly found in small quantities (one or two caterpillars per dozen trees) and, accordingly, there is little harm from it. Another thing is when there is a mass reproduction of an insect or, as this state of the population is also called, an outbreak of numbers. The reasons for this can be very different. For example, drought: after two or three warm dry seasons, instead of the usual two years, caterpillars manage to develop in a year. As a result, butterflies born in the past and the year before lay eggs this year. The population density doubles, and natural enemies - insects-entomophagous, usually destroying almost all individuals of the silkworm - manage to hit only half of its ovipositors and caterpillars, while the rest develop unhindered, pupate, turn into butterflies and give offspring. In addition, the increase in the number of silkworms may be associated with spring ground fires. The fact is that the caterpillars spend the winter under the forest floor, from where they emerge with the first thawed patches and rush into the crowns of trees. The worst enemy of the silkworm, the microscopic egg-eater telenomus, also hibernates in the litter ( Telenomus). Its females attach themselves to the body of a silkworm (up to 50 telenoms on one butterfly), travel on considerable distances to the place of laying eggs, after which they hit them. Since the silkworm lays eggs towards the middle of summer, egg-eaters are in no hurry to leave the litter. Even a light fire that has passed through the dried grass in early spring destroys b about most of the population of these insects, which contributes to the emergence of centers of mass reproduction of the silkworm. After two or three years, the caterpillars completely destroy the needles even on the largest tree and then crawl to neighboring areas in search of food.
In Siberia, such centers of mass reproduction (silkworms) are formed in forests of two types: pure (single-species) larch forests (in Yakutia, Khakassia and Tuva) and in dark coniferous taiga (in Altai, in Novosibirsk, Kemerovo, Tomsk, Irkutsk regions and Krasnoyarsk Territory). The consequences of outbreaks in these two types of forests are quite different because different types trees tolerate the invasion of the silkworm in different ways.
Larch within a month after damage is able to form secondary (compensatory) needles, which are longer, lighter than the original and have less photosynthetic activity. Nevertheless, this needle is enough to help the tree survive the loss of the crown. As a rule, larch suffers one- and two-time damage by caterpillars. The exceptions are areas with adverse conditions growth: arid, like Tuva, or permafrost, like Evenkia.
In the dark coniferous Siberian taiga, if there is larch, then in small quantities, the silkworm does not eat the leaves of aspen and birch, so the fate of the taiga depends on the stability of Siberian fir (60-100% of the forest stand), spruce and cedar. Fir and spruce are not capable of forming secondary needles and dry out after a single overeating. Cedar, on the other hand, with the same trunk diameter, has twice the biomass of needles than that of fir. Accordingly, in order to destroy the crown of a cedar, caterpillars need twice as much time or twice as many. However, this feature of the cedar does not change the situation.
It is believed that dark coniferous forests after death will sooner or later recover naturally due to succession - consecutive shift some biocenoses with others (grass community - deciduous and, finally, coniferous forest). This is true, but not in the case when the death of the taiga is caused by the mass reproduction of the silkworm. Unfortunately, not only the townsfolk, who see no reason for concern, are mistaken, but also forestry workers.
In reality, after the outbreak of the silkworm population, the following happens. All coniferous trees, including the younger generation, die, the remains of crowns crumble. The amount of light reaching the ground is doubled. As a result, forest grasses begin to grow, which were previously in a depressed state due to shading, and after a year or two the soil is hidden under a dense grass cover. Reed grass predominates among herbs ( Calamagrostis) - a cereal that causes the rapid formation of sod (a surface layer of soil penetrated by densely intertwined roots and underground shoots). A dead stand does not take moisture from the soil, as a result of which a swamp gradually forms under the silkworms. The trunks of dead trees rot and begin to fall five to seven years after the outbreak. Within 10 years, the area of mass reproduction of the silkworm turns into a dump of rotting wood. Such areas are impassable not only for humans, but also for animals.
Change of vegetation in the taiga ecosystem, where the needles were destroyed by the Siberian silkworm.
The numbers indicate the approximate number of years required to complete each stage of succession.
It takes 10-20 years for the microorganisms to destroy the remnants of wood and gradually make room for young birch trees. However, in most cases, the growth of a new generation of trees is hindered by fires. It is known that silkworms burn several times, so as long as combustible residues remain in the former hearth, trees do not grow there. In fact, during the first three decades, silkworms do not produce wood. Only after the disappearance of the fire danger, the growth of birch begins.
Even 50 years after the mass reproduction of the silkworm, the former taiga area is covered with dense thickets of birch with a trunk diameter of 2-8 cm. about 20 cm). How long does it take for the original taiga vegetation to recover in such an area?
To begin with, soil moisture should decrease, since the main species that determines the appearance of dark coniferous forests on the plain is fir, which does not tolerate waterlogging. It can be expected that within a few decades the growing birch forest will drain the soil and it will become suitable for fir seedlings.
But where do the seeds come from in the silkworm? A certain amount of pine nuts can be brought by birds, but their role cannot be overestimated. Spruce seeds, sown from cones in winter, can be brought by the wind along the crust. However, the most important thing is the natural sowing of fir - the main forest-forming species. Fir cones disintegrate in autumn. At the same time, the seeds do not fly far: special measurements show that the range of their distribution does not exceed 100 m, and the bulk settles 50-60 m from the mother trees. It turns out that silkworms have a chance to be sown sooner or later only if they have a small area.
So it is, but coniferous seedlings, even if they were able to take root in the sod (which is unlikely), there is no way to compete with reed grass, which grows incomparably faster. This circumstance fully corresponds to the established fact: on the border of the silkworm, all young coniferous trees are concentrated in a hundred-meter strip along the forest edge, which annually produces seeds of fir, spruce and cedar. At the same time, only cedar and spruce are represented in the undergrowth; fir is present singly. Moreover, the density of undergrowth is only 200-300 specimens per hectare, and for forest restoration, their number should be at least ten times higher.
So, contrary to popular belief, the natural restoration of dark coniferous forests after their destruction by the silkworm is unlikely: rare trees appear only in close proximity to a healthy forest. Let's add to this that the area of 20-30 thousand hectares is not the limit for the silkworm. It is clear that the probability of getting a sufficient number of seeds into the silkworm is low, and the successful development of seedlings and the further growth of a new generation of conifers is practically impossible. As a result, after repeated fires, growth and subsequent natural thinning of birch thickets, approximately in the sixth or eighth decade after the mass reproduction of the silkworm, a birch sparse forest appears on the site of the dark coniferous taiga.
There is another misconception: silkworm outbreaks occur at intervals of 11-13 years. To doubt this, one need only look at a simple chronicle of recent events. During the decade from 1992 to 2001, silkworm foci were noted in Novosibirsk oblast. (1995-1999), in Tomsk (1995-1996 and 2000-2001), in Altai and Tuva (1992-2001), in the Kemerovo region. (1998-2000), in Khakassia (1999-2000), in the Krasnoyarsk region (1992-1997 and 2000-2001), in the Irkutsk region. (1995-2001), in Buryatia (1992 and 1997-2001), in the Chita region. (1999-2001), in Yakutia (2000-2001). At the same time, foci with a total area of more than 50 thousand hectares were found in Altai, Tuva, Irkutsk region. and others. Only in the Krasnoyarsk Territory for three years (1992-1995) silkworms killed fir forests on an area of 260 thousand hectares; in some areas, almost a fifth of all dark coniferous forests disappeared. I note that this is information from official forestry statistics, reporting only on the foci found, but not on all active foci.
The conclusion is obvious: in Siberia, the silkworm annually damages forests on an average of about 100 thousand hectares, a significant part of which turns into vast treeless spaces; accordingly, the activity of the silkworm is difficult to characterize otherwise than as an ecological disaster.
Theory and practice
They say that preventing a disease is easier than curing it, and one cannot but agree with this. Outbreaks of phytophage numbers are an obvious pathology of the biocenosis, from which all organisms inhabiting it suffer. The pest itself is no exception: for many years after the mass reproduction of the silkworm, it is difficult to detect in the vicinity of the outbreaks.
To establish the beginning of mass reproduction, monitoring is carried out - a set of measures to monitor the number of pests. If the number has exceeded a certain threshold, then the treatment (usually from the air) of the emerging foci with chemical or bacterial insecticides is prescribed.
The theory is good, but the reality is more complicated. The forests of Siberia are difficult to access at best, so monitoring can only be carried out in relatively few areas. Even if an increase in numbers is noted in some of them, it is almost impossible to establish the true boundaries of the beginning outbreak. This is exactly what happened in the Krasnoyarsk Territory in 1990-1992, when the impending catastrophe was forestalled two years in advance and appropriate measures were taken. However, the ensuing mass reproduction led to the formation of foci in the territory of 250-120 km; it is technically impossible to cover such an area with aerial treatments, not to mention the cost of such activities. It is reasonable to assume that the centers of the Siberian silkworm will continue to form. What to do?
Funds from the Russian forestry arsenal are few. One of the methods actively discussed these days is the so-called “controlled burning”, a technology imported into Russian forestry practice, as always, from the USA, where burning is used quite often. However, even with American technology and organization, the fire is not always managed to be kept under control, and then much more burns than was planned. In Russia, under the existing circumstances, the fire has much more opportunity to escape into the surrounding forests. The consequences of burning dry forest stands on an area of several thousand hectares are quite obvious. Due to these circumstances, one can hardly expect that the burning of silkworms will take any significant place in domestic practice.
Atmospheric explosion of accumulation of underoxidized substances,
formed during combustion in conditions of lack of oxygen, -
one of the phenomena accompanying large forest fires.
Photo by V.I.Zabolotsky
It remains only to chop the silkworms; both economic and environmental considerations lead to this conclusion. Otherwise, the silkworm will rot and pose a constant fire hazard. Suffice it to say that the volume of dead wood in the already mentioned Krasnoyarsk silkworms amounted to about 50 million m 3 . What impact will the astronomical amount of decay and combustion products emitted into the atmosphere have on climate processes? What will be the geographic scope of this influence? The significance of this aspect of silkworm activity has yet to be assessed.
It is obvious that the Siberian silkworm poses a real threat to the very existence of the fir taiga on the plains of Western and Eastern Siberia. Consequently, the introduction of a specially protected area regime is required, at least for that part of the forests where Siberian fir dominates, if these forests are located in the zone of the harmful effect of Siberian silkworm populations.
An anthropogenic crisis?
It is assumed that outbreaks of the Siberian silkworm are a natural, evolutionarily determined phenomenon. Otherwise, one would have to believe that the ecosystem is capable of self-destruction: after all, the Siberian silkworm is not an alien species, not an invader, but an original taiga inhabitant, i.e. part of the ecosystem. But how, in this case, could the dark coniferous taiga of Siberia - the root forest formation - arise in the conditions of permanent large breeding centers of the silkworm? Another explanation looks more realistic: outbreaks of this insect arose relatively recently as a result of a disruption in the balanced functioning of taiga ecosystems, which could be caused by human agricultural and logging activities that began in Siberia less than four centuries ago. Fire farming led to the fragmentation of biocenoses and the formation of heated forest edges. The sudden lightening of the crown has a depressing effect on the fir and suppresses its protective reaction to insect damage. It is possible that the increase in temperature and the suppression of the immunity of the forage plant once accelerated the development of the Siberian silkworm and allowed it to elude the numerous natural enemies that regulate its numbers. As a result, the system went out of balance - human activity served as a trigger for a process that destroys the natural biocenosis.
This point of view is in good agreement with the fundamental idea of V.V. Zherikhin about the evolution of biological communities, developed on the basis of a deep comparative study of the change of fossil faunas. The development of life on Earth has repeatedly passed through periods of mass extinction of some and the emergence of other creatures. The change in the composition of the fauna occurred against the background (and because of) the ecological crisis caused by depression and the disappearance of dominants (edificators) - plants that determined the appearance and structure of ecosystems of the distant past. In place of extinct communities, new ones arose. In particular, all stable grass communities (steppes, prairies, pampas) historically formed on the site of succession series with forest climaxes due to the loss of the last stages dominated by trees. The latter is understandable: in any series of community change, the most vulnerable stage is the initial one; if it were stable, there would be no succession at all. Therefore, if the final stages are regularly destroyed by some factor and the successional system returns to its original state, then there is a possibility that the ecological space will be captured by other species that will not allow further changes in cenoses along the knurled path. “Other species” are not aliens, but inhabitants of local ecosystems, usually in a depressed state, but able to grow rapidly and hold the territory when suitable conditions occur. In the situation with the taiga and the Siberian silkworm, the role of the invader species is played by the reed grass.
The observed pattern is not identical to those known from paleoecology. Fossil forests have disappeared with the active participation of large leaf-eating mammals, while the dark coniferous taiga is being destroyed by insects. And yet, the fundamental scheme is repeated: the consumer of the first order transfers the forest ecosystem to the initial stage of succession, after which the position of the edificator in the plant community is occupied by one of the common, but not previously dominant species, which modifies the environment in such a way that the path to the former climax ecosystem is closed. .
If the noted similarity is not superficial, then the presented example illustrates the process of the anthropogenic biospheric crisis, which V.V. Zherikhin repeatedly spoke about - a radical restructuring of the entire biota caused by human activity. Of course, the crisis did not start now: outbreaks of locusts plagued people long before our era. But biocenotic crises do not occur overnight. anomalous natural phenomena have been following the development of civilization for thousands of years, the established structure of the biosphere is being shaken slowly and little by little, but you still need to think about the consequences.
Literature
1. Kolomiets N.G. Siberian silkworm - a pest of the lowland taiga // Tr. according to the forest hoz-vu. Novosibirsk, 1957. Issue 3. pp.61-76. 2. Kuzmichev V.V., Cherkashin V.P., Korets M.A., Mikhailova I.A.// Forest science. 2001. No. 4. pp.8-14 3. Savchenko A.M. On the distance of scattering of seeds of Siberian fir in lowland forests // Tr. SibNIILP. 1966. Issue 14. S.3-5. 4. Kondakov Yu.P. Patterns of mass reproduction of the Siberian silkworm // Ecology of populations of forest animals in Siberia. Novosibirsk, 1974. S.206-265. 5. Official data of the Russian Center for Forest Protection. 6. Talman P.N. The influence of the environment and the human role that transforms it in connection with the reproduction of the Siberian silkworm // Tr. LTA. 1957. Issue 81. Part 3. pp.75-86. 7. Zherikhin V.V. Selected works on paleoecology and phylocenogenetics. M., 2003.
A dangerous pest of forests and cultural plantations, the gypsy moth has a wide distribution area. This pest can be found in Asia, Europe, North Africa, North America. It covers the entire territory of Russia, is found in the south, in Siberia and the Far East. Deciduous trees are especially affected by caterpillars. In the absence of food, silkworms move to young coniferous trees. Once in the nursery, insects can cause significant damage to plantings.
What does a gypsy moth butterfly look like
The gypsy moth is a butterfly belonging to the Lepidoptera order from the family of volnyanka. Distinctive feature of these insects, there are noticeable differences between males and females.
Differences in adults are noticeable in color and shape:
- Females - the size of the wings in the unfolded state reaches 90 mm. The thick body has the shape of a cylinder. A grayish fluff is noticeable on the abdomen. The antennae are thin and long.
- Male - wingspan 40-50 mm, body thin, covered with hairs. The color of the wings is brown, the surface is covered with a pattern of dark spots and broken lines. Antennae combed.
Gypsy moth butterflies prefer woodlands, dry places with enough light. The first centers of distribution are usually located on the edges. During droughts, large outbreaks of mass reproduction of silkworms occur. This species is the leader among pests in terms of the number of breeding outbreaks and the duration of these periods.
Silkworm breeding
Heavy females rarely fly, they sit on the bark of trees and attract males with the help of pheromones. Males start years a few days earlier. They are especially active in the evening. In search of a mate, they fly long distances. After fertilization, the females lay their eggs under the bark of trees at a height of 3-4 m. They are round, yellow or pinkish in color. Size - 1 mm, the number of eggs in the clutch of gypsy moth - 100-1000 pieces. In the egg state, the insect spends most of its life - about 8 months.
An embryo is formed inside the egg shell, which remains to winter. In spring, when the temperature rises to +10 0, the first caterpillars appear. For some time they sit motionless, then spread out over the tree. The body of small caterpillars is covered with bristles and air bubbles. This allows them to travel with gusts of wind. For movement over considerable distances, insects can release webs.
Interesting fact. The caterpillar is the only form of non-greenhouse that feeds, accumulating energy for the remaining phases of development.
The gypsy moth belongs to the cocoon moth family. The caterpillar appears with sixteen legs. At birth, it is light yellow, but quickly darkens and turns brown or black. There are several longitudinal rows of warts on the body.
Information. Gypsy moth eggs are extremely viable, they are able to withstand frosts down to -50.
After settling in a new territory, active feeding begins. Young caterpillars eat during the daytime, gnawing small holes in the leaves. After 3-4 months, they switch to eating at night, eating the leaf completely. In addition to foliage in the diet of pests, buds, young shoots, flowers. Depending on the climate zone caterpillars take 50 to 80 days to develop. Then they pupate. This occurs in June-July, the pupal stage lasts 10-15 days.
Information. Optimum temperature+20-25 for insect growth, if it drops to +10, development stops. Male caterpillars go through 5 stages of larvae to the stage of adults (adult), females - 6 stages.
Distribution and harm
The pest has a wide distribution area. In Europe, it is found up to Scandinavia, in Asia it covers many countries: Israel, Turkey, Afghanistan, Japan, China, Korea. An interesting story of a butterfly getting into North America. The insect was introduced artificially for crossbreeding experiments with other species. The larvae were able to spread from the experimental area to open forests. The problem that arose was not given due importance, and over the course of several years, the non-partners captured a vast territory. Only in 1889, the gypsy moth was recognized as a pest. But the insect is already firmly entrenched in the new territory.
Interesting fact. Due to the wide range of distribution of butterflies, they are divided into races. In Russia, there are Far Eastern, European, Siberian and other races.
The gypsy moth caterpillar exposes deciduous trees in forests and gardens. She prefers fruit plantations of apple trees, plums, apricots. AT wild nature chooses oak, birch, linden. Bypasses ash and alder. In total, the pest eats about 300 plant species, including conifers. The main division occurs on the European and Asian races. The Asian group is a real polyphage, feeding on various types of trees and bushes.
Varieties of gypsy moths
Butterflies of gypsy moths are classified as different species depending on the place of residence and nutritional habits. Common groups include:
This is a small representative of its kind. The size of the wings of females is 40 mm, males 30 mm. The insect is common in Europe and Asia. The caterpillar will grow up to 55mm and is gray-blue in color with white and yellow stripes. Pests live in colonies, create spider nests. When fighting gypsy moth it is necessary to cut and burn the branches where the ovipositor is seen. The trees themselves are sprayed with insecticides.
Male and female oddball
Walking silkworm
The marching silkworm is characterized by the ability of caterpillars to migrate to new feeding grounds. At the same time, they line up in a long chain, following each other. The first caterpillar, which is the leader, releases a silk thread along which the rest of the insects are guided. There are two types of marching silkworms - oak and pine.
Pine cocoonworm
Insects are common in the coniferous forests of Siberia and Europe. They damage pine plantations, less often than other species. Grayish-brown females are 85 mm in size, males - 60 mm, caterpillars - up to 80 mm. Caterpillars spend the winter in the ground under tree trunks. In the spring they rise to feed, pupate in July.
Siberian silkworm
The unpaired Siberian silkworm feeds on coniferous trees. This species damages spruce, pine, cedar and fir. The insect settled in the forest and forest-steppe zone of Siberia. The northern limit of its distribution runs along the Arctic Circle. The development of a silkworm from egg to butterfly in a cold region takes 2 years. AT warm years it can accelerate to a one-year cycle. Butterflies of the Siberian silkworm are distinguished by a variety of colors. There are adults of brown, gray, black color. The wingspan of females is 6-10 cm, males are more modest in size - 4-7 cm. Three dark jagged stripes run across the front wings. Hind wings are brown. The head and thorax are the same color as the forewings.
The clutch of butterflies is bluish in color, the size of the eggs is 2 mm. They are deposited in uneven piles of 100 pieces. They are located in the bark, on needles and twigs. When the larva appears, it eats half of the shell. Caterpillars grow up to 11 cm, their bodies are gray or black. There are blue hairs on the back. Insects are able to take a threatening posture. At the same time, they raise the front of the body and bend their heads. A bright yellow stripe runs along the sides. The body is covered with hairs, they are the longest in the front and on the sides.
The head of the caterpillar is brown, with orange spots on the abdomen. The pupa of the Siberian silkworm is dark, almost black. Its length is up to 5 cm, the cocoon is suspended on branches or between needles. Burning hairs are woven into its shell. There are three races of local silkworms:
- larch;
- fir;
- cedar.
Silkworm caterpillars calmly endure the cold, they leave for wintering at a temperature close to 0 0. They crawl onto trees after wintering immediately after the snow melts. As it grows, frost resistance increases.
Information. With frosts down to -10, the caterpillars die, and they do not survive winters with little snow.
Pest Control Methods
Identification of the neparnik occurs by gnawed leaves, excrement, butterflies and ovipositors in the web. Basic information is taught by studying adults and the number of eggs in a clutch. This provides information for the forecast, allows you to determine the phase of the outbreak. Methods of pest control are chosen depending on the degree of their distribution.
Attention. The Siberian and Far Eastern races of silkworms represent a quarantine danger. Cargo is carefully inspected and Vehicle following from the Siberian region. Pests are lured out with pheromone traps.
How to deal with gypsy moth in your garden? Trees should be carefully monitored. When signs of damage by caterpillars appear, start the destruction of the ovipositors. They are visible among the foliage, nests are cut and burned along with eggs. Caterpillars can be harvested by hand, a tedious procedure that can be done in small areas. Effective method- the device of glue rings, crawling caterpillars will stick to the surface of the traps. In autumn, egg clutches are scraped from the bark of trees.
Attention. Wear protective gloves when handling pests.
The use of insecticides is the most effective measure to control the gypsy moth in the garden and woodland. At the beginning of spring, trees are treated with Chlorophos, Metaphos, as well as organophosphorus compounds.
The Siberian silkworm is a butterfly from the cocoonworm family, whose caterpillars feed on the needles of almost all coniferous species found within its range. Larch is preferred, fir and spruce are also often damaged. To a lesser extent, pines are damaged - Siberian and ordinary.
Appearance
The Siberian silkworm is a large butterfly: the wingspan of the female is 60-80 mm, the male is 40-60 mm. Males have feathery antennae.
The color of the wings varies from light yellowish brown or light gray to almost black. Forewings with three dark stripes. In the middle of each wing there is a large white spot, the hindwings are one-colored.
Eggs are almost spherical in shape, up to 2 mm in diameter. Their coloration is at first bluish green with a dark brown dot at one end, then becomes grayish. A clutch usually contains several dozen eggs (up to 200).
Caterpillars reach a length of 55-70 mm. Their coloration, like that of adults, is variable and varies from gray-brown to dark brown. On the 2nd and 3rd segments of the body of the caterpillar there are black transverse stripes with a bluish tint, and on the 4th-12th segments there are black horseshoe-shaped spots.
The pupae are 28-39 mm long, their integuments are initially light, brownish-red, becoming dark brown, almost black as they develop.
Spreading
On the territory of Russia, the species is distributed within the Ural, West Siberian, East Siberian and Far Eastern regions, it is important as a forest pest from Southern Urals to the coast of the Sea of Japan and the Sea of Okhotsk. In the north, the range of the species reaches Yakutia. Outside of Russia, the Siberian silkworm is distributed in Mongolia, Kazakhstan, Korea, and northeast China. The southern border of the range runs at 40 ° C. sh. It is noted that the range of the Siberian silkworm is moving to the west.
Life cycle
The flight of butterflies begins in the second half of July and lasts about a month. Imagoes of the Siberian silkworm do not feed. The female lays on average about 300 eggs. Eggs are placed singly or in groups on needles at the top of the crowns. Egg development lasts from 13 to 22 days. In the second half of August, caterpillars of the first age emerge from the eggs, which feed on green needles. At the end of September, having reached the second or third age, the caterpillars leave for the winter. Wintering occurs in the litter under moss and coniferous litter. In May, after the snow melts, the caterpillars rise to the crowns, where they feed until the next autumn. The second wintering of caterpillars occurs at the fifth or sixth age, after which they return to the crowns in spring. After active feeding in June, caterpillars pupate in dense gray cocoons. Pupa development lasts 3-4 weeks
