What plants does the Siberian silkworm harm? How dangerous is the Siberian silkworm? Difference between the pine cutworm and the Siberian silkworm

The Siberian silkworm is a butterfly from the cocoon moth 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. Pines - Siberian and Scots - are damaged to a lesser extent.

Appearance

Siberian silkworm - large butterfly: wingspan of the female is 60-80 mm, of the male - 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. There is a large white spot in the middle of each wing; the hind wings are the same color.

The eggs are almost spherical in shape, up to 2 mm in diameter. Their color is first bluish-green with a dark brown dot at one end, then becomes greyish. There are usually several dozen eggs in a clutch (up to 200 pieces).

Caterpillars reach a length of 55-70 mm. Their color, like the color of the imago, is variable and varies from gray-brown to dark brown. On the 2nd and 3rd segments of the caterpillar's body 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 covers are initially light, brownish-red, and as they develop they become dark brown, almost black.

Spreading

On the territory of Russia, the species is distributed within the Ural, West Siberian, East Siberian and Far Eastern regions, and is important as a forest pest from Southern Urals to the coast of the Sea of Japan and Okhotsk. In the north, the species' range 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. w. Range advancement is noted Siberian silkworm to the west.

Life cycle

The flight of butterflies begins in the second half of July and lasts about a month. Siberian silkworm adults do not feed. The female lays an average of about 300 eggs. Eggs are placed singly or in groups on needles in the upper part of the crowns. Egg development lasts from 13 to 22 days. In the second half of August, first instar caterpillars emerge from the eggs and feed on green needles. At the end of September, having reached the second or third instar, the caterpillars leave for the winter. Overwintering occurs in the litter under moss and pine litter. In May, after the snow melts, the caterpillars rise into the crowns, where they feed until the following autumn. The second wintering of the caterpillars occurs at the fifth or sixth instar, after which they return to the crowns in the spring. After active feeding in June, the caterpillars pupate in dense gray cocoons. Pupa development lasts 3-4 weeks

Siberian silkworm
and the fate of the fir taiga

D.L. Grodnitsky

Dmitry Lvovich Grodnitsky, Doctor of Biological Sciences,
head department natural disciplines Institute for Advanced Training of Education Workers (Krasnoyarsk).

Who hasn’t heard about the gluttony of locusts, which, when multiplying en masse, unite in swarms of many millions, fly hundreds of kilometers in search of food, and in a matter of hours destroy grain and cotton crops, orchards and vineyards, and eat not only leaves, but also branches, and even bark? from the trees? Many times, locusts doomed hundreds of thousands of people to starvation. Those lucky enough to survive the invasion erected monuments in honor of their salvation. However, locusts rage mainly in the tropics and subtropics, while for Siberian forests a real disaster is the mass reproduction of a lesser-known, but no less voracious insect - the Siberian silkworm ( 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 advance across the European part of Russia.

An adult Siberian silkworm is a large butterfly up to 10 cm (usually four to seven) in wingspan; males are smaller than females. Butterflies don't eat (they don't even have a proboscis), but caterpillars have an excellent appetite. They eat the crowns of all types 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) sets in, when they hardly eat. By the way, the caterpillars of another pest (also quite large in size) - gypsy moth (Lymantria dispar) - feed continuously and completely complete development within one and a half months, but the life cycle of the Siberian silkworm usually stretches for two years. The biological meaning of short-term diapause in summer, when everything seems to favor the growth and development of the larva, is still unclear.

Ecological disaster?

The Siberian silkworm is a common inhabitant of forest ecosystems; in a healthy forest it is constantly found in small quantity(one or two caterpillars per ten trees) and, accordingly, there is little harm from it. Another thing is when a mass reproduction of an insect occurs or, as this population state 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, caterpillars manage to develop in a year instead of the usual two years. As a result, butterflies born last year and the year before lay eggs this year. The population density doubles, and natural enemies - entomophagous insects, which usually destroy almost all individuals of the silkworm - manage to infect only half of its egg-laying eggs and caterpillars, while the rest develop unhindered, pupate, turn into butterflies and give birth to offspring. In addition, the increase in silkworm numbers 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 tree crowns. Overwinters in the litter and worst enemy silkworm - microscopic ovi-eater telenomus ( Telenomus). Its females attach to the body of the silkworm (up to 50 telenomus on one butterfly), travel considerable distances to the place where eggs are laid, and then infect them. Since the silkworm lays eggs closer to mid-summer, the egg eaters are in no hurry to emerge from the litter. Even a light fire that passes through dried grass in early spring destroys b O most of the population of these insects, which contributes to the emergence of centers of mass reproduction of silkworms. After two or three years, the caterpillars completely destroy the needles of even the largest tree and then crawl to neighboring areas in search of food.

In Siberia, such centers of mass reproduction (silkworms) are formed in two types of forests: pure (uniform) larch forests (in Yakutia, Khakassia and Tuva) and in dark coniferous taiga (in Altai, Novosibirsk, Kemerovo, Tomsk, Irkutsk regions and Krasnoyarsk Territory). The consequences of outbreaks in these two types of forests are completely different because different types Trees tolerate silkworm infestation differently.

Within a month after damage, larch is capable of forming secondary (compensatory) needles, which are longer, lighter than the original ones and have less photosynthetic activity. Nevertheless, these needles are enough to help the tree survive the loss of the crown. As a rule, larch suffers single and double damage from caterpillars. The exception is areas with unfavorable conditions growth: arid, like Tuva, or permafrost, like Evenkia.

In the dark coniferous Siberian taiga, if there is larch, it is in small quantities; silkworms do not eat aspen and birch foliage, so the fate of the taiga depends on the sustainability of Siberian fir (60-100% of the tree stand), spruce and cedar. Fir and spruce are not capable of forming secondary needles and dry out after being eaten once. Cedar, with the same trunk diameter, has twice the biomass of needles than fir. Accordingly, to destroy the cedar crown, the caterpillars need twice as much time or twice the number. However, this feature of cedar does not change the situation.

It is believed that dark coniferous forests, after death, will sooner or later recover naturally thanks to succession - the consistent replacement of some biocenoses by others (herbaceous 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 silkworms. Unfortunately, not only ordinary people who see no reason to worry are mistaken, but also forestry workers.

In reality, after an outbreak of silkworm numbers, the following happens. All coniferous trees, including the younger generation, die, the remains of the crowns crumble. The amount of light reaching the ground doubles. As a result, forest grasses, which were previously in a depressed state due to shading, begin to grow, and after a year or two the soil is hidden under a thick grass cover. Reed grass predominates among the herbs ( Calamagrostis) is a grass that causes the rapid formation of sod (a surface layer of soil penetrated by densely intertwined roots and underground shoots). The dead tree 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 silkworm breeding area 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 microorganisms to destroy the remaining wood and gradually make room for young birch trees. However, in most cases, fires prevent the growth of a new generation of trees. It is known that silkworms burn several times, so while flammable residues remain in the former hearth, trees will not grow there. In fact, during the first three decades, silkworms do not produce wood. Only after the fire danger disappears does the birch tree begin to grow.

Another 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. Under the birch there is the same cover of reed grass, under the reed grass there is turf, under the turf there is waterlogged soil ( groundwater lie at a depth of only about 20 cm). How long does it take for the original taiga vegetation to be restored in such an area?

First, the soil moisture must decrease, since the main species that determines the appearance is dark coniferous forests on the plain - fir, which does not tolerate waterlogging. It can be expected that within several decades the growing birch forest will dry out 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 may be brought by birds, but their role cannot be overestimated. Spruce seeds sown from cones in winter can be carried by the wind along the crust. However, the most important thing is the natural sowing of fir - the main forest-forming species. Fir cones fall apart in the fall. At the same time, the seeds do not fly far: special measurements show that their distribution range 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.

This is true, but coniferous seedlings, even if they were able to take root in the turf (which is unlikely), do not have the opportunity 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 only sporadically. Moreover, the density of undergrowth is only 200-300 specimens per hectare, and for forest restoration their number must be at least ten times greater.

So, contrary to popular belief, the natural restoration of dark coniferous forests after their destruction by silkworms is unlikely: rare trees appear only in close proximity to a healthy forest. Let's add to this that an area of 20-30 thousand hectares is not the limit for the silkworm. It is clear that the probability of a sufficient number of seeds getting 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 to eighth decade after the mass reproduction of silkworms, a birch woodland appears in place of the dark coniferous taiga.

There is another misconception: outbreaks of silkworms occur every 11-13 years. To doubt this, just look at a simple chronicle latest events. During the decade from 1992 to 2001, outbreaks of silkworms were noted in the Novosibirsk region. (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 Territory (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, the outbreaks total area more than 50 thousand hectares were discovered in Altai, Tuva, and Irkutsk region. etc. In the Krasnoyarsk Territory alone, in 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. Let me note that this is information from official forestry statistics, reporting only on those found, but not on all active outbreaks.

The conclusion is obvious: in Siberia, every year the silkworm damages forests on an average area of about 100 thousand hectares, a significant part of which turns into vast treeless spaces; Accordingly, the activity of the silkworm can hardly be characterized as anything other than an environmental disaster.

Theory and practice

They say that preventing a disease is easier than treating it, and one cannot but agree with this. Outbreaks in the number of phytophages are an obvious pathology of the biocenosis, from which all organisms inhabiting it suffer. The pest itself is no exception: for many years after mass reproduction of silkworms it is difficult to detect in the vicinity of 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 treatment (usually from the air) of the emerging foci with chemical or bacterial insecticides is prescribed.

The theory is good, but reality is more complicated. Siberian forests 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 disaster was anticipated two years in advance and appropriate measures were taken. However, the subsequent mass reproduction led to the formation of foci over an area of 250-120 km; It is technically impossible to cover such an area with aerial treatments, not to mention the cost of such measures. It is reasonable to assume that foci of Siberian silkworms will continue to form. What to do?

The resources in 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 cannot always be kept under control, and then much more is burned than planned. In Russia, under current circumstances, the fire has much more opportunities to escape into the surrounding forests. The consequences of fires in dry forest stands over an area of several thousand hectares are quite obvious. Due to these circumstances, it can hardly be expected that burning silkworms will occupy any significant place in domestic practice.

Atmospheric explosion of an accumulation of under-oxidized substances,
formed during combustion in conditions of lack of oxygen, -
one of the phenomena accompanying large forest fires.
Photo by V.I. Zabolotsky

All that remains is to cut down 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 was about 50 million m3. What impact will the astronomical amount of decay and combustion products released into the atmosphere have on climate processes? What will be the geographic scope of this influence? The significance of this aspect of silkworm activity remains to be assessed.

It is obvious that the Siberian silkworm represents real threat the very existence of the fir taiga on the plains of Western and Eastern Siberia. Consequently, it is necessary to introduce a specially protected area regime for at least that part of the forests where Siberian fir dominates, if these forests are located in the zone of harmful action of Siberian silkworm populations.

A man-made crisis?

It is assumed that outbreaks in the number of Siberian silkworms 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 a primordial taiga inhabitant, i.e. part of the ecosystem. But how, in this case, could the dark coniferous taiga of Siberia - an indigenous forest formation - arise in the conditions of constantly operating large breeding centers of silkworms? Another explanation seems more realistic: outbreaks in the number 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 edges. Sudden lightening of the crown has a depressing effect on the fir and suppresses its protective reaction to damage by insects. It is possible that rising temperatures and suppressed host plant immunity once accelerated the development of the Siberian silkworm and allowed it to escape the numerous natural enemies that regulated 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 V.V. Zherikhin’s fundamental idea of the evolution of biological communities, developed on the basis of an in-depth comparative study of the succession of fossil faunas. The development of life on Earth has repeatedly passed through periods of mass extinction of some creatures and the emergence of other creatures. The change in the composition of the fauna occurred against the background (and because of) an ecological crisis caused by depression and the disappearance of dominants (edificators) - plants that determined the appearance and structure of ecosystems in 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 successional series with forest climaxes due to the loss last stages where trees dominated. The latter is understandable: in any series of changes in communities, 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 succession 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 established path. “Other species” are not aliens, but inhabitants of local ecosystems, usually in a depressed state, but capable of growing quickly and maintaining territory when suitable conditions arise. In the situation with the taiga and the Siberian silkworm, the role of the invader species is played by the reed grass.

The observed picture is not identical to that known from paleoecology. Fossil forests disappeared when active participation large leaf-eating mammals, while the dark coniferous taiga is destroyed by insects. And yet the principle is repeated: the consumer of the first order translates forest ecosystem at the initial stage of succession, after which the position of the edifier in the plant community is occupied by one of the common, but previously not 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 biosphere 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 begin now: locust outbreaks plagued people long before our era. But biocenotic crises do not happen overnight. Abnormal natural phenomena For thousands of years, following the development of civilization, the existing 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 lowland taiga // Tr. according to forest household Novosibirsk, 1957. Issue 3. P.61-76.

2. Kuzmichev V.V., Cherkashin V.P., Korets M.A., Mikhailova I.A.// Forestry. 2001. No. 4. P.8-14

3. Savchenko A.M. On the dispersion distance of Siberian fir seeds in lowland forests // Tr. SibNIILP. 1966. Issue 14. P.3-5.

4. Kondakov Yu.P. Patterns of mass reproduction of the Siberian silkworm // Ecology of populations of forest animals of Siberia. Novosibirsk, 1974. P.206-265.

5. Official data of the Russian Forest Protection Center.

6. Talman P.N. The influence of the environment and the transformative role of humans in connection with the reproduction of the Siberian silkworm // Tr. LTA. 1957. Issue 81. Part 3. P.75-86.

7. Zherikhin V.V. Selected works on paleoecology and phylocenogenetics. M., 2003.

The coniferous forest is in serious danger, its future is in jeopardy if short time no effective measures will be taken to combat the worst pest of conifers– Siberian silkworm (Dendrolimus superans). More and more of it began to be found in the coniferous forests of Russia. How dangerous is the Siberian silkworm, and what are the destructive consequences of its invasion for the healthy existence of coniferous forests?

The Siberian silkworm butterfly is inconspicuous at first glance and appears to be absolutely safe. But this is far from true. These pests are increasingly caught in special traps, and scientists have sounded the alarm: the population of this pest is growing rapidly. In fact, the ten-centimeter insect is not so dangerous, especially for coniferous forests, and damage to forest plantations is caused by its caterpillars hatching from eggs. They are able to quickly acclimatize, are quite hardy, and have an excellent appetite.

An adult Siberian silkworm lays its eggs on the branches of coniferous trees. Hatching, the larva immediately begins to eat, moving from the lower crown to the very top, leaving behind only eaten branches. In October, the Siberian silkworm larva goes to winter, and in the spring of next year the third instar larva also continues to feed throughout the warm season. Siberian silkworm caterpillars eat almost all coniferous tree species. After the fifth instar, the more voracious larva again leaves for the winter, after which a butterfly appears and actively begins to lay eggs. In just one season, a female can lay about 800 eggs.

The Siberian silkworm is dangerous because it can cause massive outbreaks of reproduction, which will ultimately lead to the global death of millions of hectares of coniferous forests. This is exactly what happened on Far East and in Siberia. Coniferous forest in these areas It simply amazes with its destruction and mass death. In these places after global growth popularity of the Siberian silkworm all coniferous forest plantations, including growing seedlings coniferous pine trees and Christmas trees died. The remains of the crowns crumbled. Scientists say that the coniferous forest will take about a hundred years to grow in its original place again.

To avoid the spread of the Siberian silkworm, Rosselkhoznadzor specialists recommend introducing a number of phytosanitary restrictions: when exporting coniferous species, they must be debarked or disinfected in order to prevent the spread of the Siberian silkworm further along coniferous forests Russia. There is now increased attention to the export and import of coniferous wood: without the appropriate accompanying certificate, such cargo may be illegal.

If you find a Siberian silkworm on the coniferous trees of your site, you must immediately organize measures to combat this pest. The natural enemies of the pine silkworm are the cuckoo, the ichneumon fly, and fungal infections.

During mass reproduction, coniferous trees should be treated with insecticides. The most effective biological drug at present is lepidocide.

And to prevent Siberian silkworms, it is necessary to regularly inspect trees for the presence of pests and carry out preventive treatment with insect repellents.

More and more of it began to be found in the coniferous forests of Russia. How dangerous is the Siberian silkworm, and what are the destructive consequences of its invasion for the healthy existence of coniferous forests?

In the Amur region, the Siberian silkworm was discovered in the Blagoveshchensk region in 2008. Compared to other subjects Russian Federation located on the territory of Siberia and the Far East, the situation with the Siberian silkworm is quite favorable. However, you should not get your hopes up, because... serious problem even one individual silkworm can create.

Periodically, approximately once every 10 years, an outbreak of the Siberian silkworm population occurs, the consequences of which are the destruction of huge areas of valuable coniferous plantations. The use of modern insecticidal pyrethroid and bacterial preparations in recent years made it possible to partially localize the pest outbreaks and stop its further spread.

At the same time, the danger of a new mass reproduction of the Siberian silkworm remains.

Periodic large-scale outbreaks of mass reproduction of the Siberian silkworm caused by biological features of this species lead to significant changes in the structure of taiga forests, destruction of tree stands and changes in forest formations.

Foci of mass reproduction are observed in Russia annually on an area from 4.2 thousand to 6.9 million hectares and cause significant damage to forestry. This is exactly what has already happened in the Far East and Siberia. The coniferous forest in these areas is simply amazing in its destruction and mass death. In these places, after the global increase in the popularity of the Siberian silkworm, all coniferous forest plantations, including growing seedlings of coniferous pines and fir trees, died. The remains of the crowns crumbled. Scientists say that the coniferous forest will take about a hundred years to grow in its original place again.

Satellite monitoring is used for timely detection of breeding foci.

In the period between outbreaks, silkworms live in reservations - areas with the most favorable development conditions. In the zone of dark coniferous taiga, reservations are located in mature, fairly productive stands of forb-green moss forest types with the participation of fir.

Externally, the Siberian silkworm is a large butterfly with a wingspan of 60-80　mm for the female and 40-60　mm for the male. Color varies from light yellowish brown or light gray to almost black. The forewings are intersected by three darker stripes. There is a large white spot in the middle of each wing; the hind wings are the same color.

Females lay eggs on needles, mainly in the lower part of the crown, and during periods of very high numbers - on dry branches, lichens, grass cover, forest floor. In one clutch there are usually several dozen eggs (up to 200 pieces), and in total the female can lay up to 800 eggs.

Siberian silkworm caterpillars have different colors. It varies from gray-brown to dark brown. The body length of the caterpillar is 55-70 mm, on the 2nd and 3rd body segments they have black transverse stripes with a bluish tint, and on the 4-120th segments there are black horseshoe-shaped spots.

At the end of April, the caterpillars climb into the crowns of trees and begin to eat whole needles, and if there is a lack of food, the bark of thin shoots and young cones. In the fall they leave for the second winter. In May-June of the following year, adult caterpillars feed intensively, causing the greatest harm. During this period, they eat 95% of the food needed for full development.

The Siberian silkworm damages about twenty species of coniferous trees - from larch to spruce. But they prefer fir, spruce, and larch. Cedar is damaged to a lesser extent, and pine is even less damaged. In June, the caterpillars pupate; before pupation, the caterpillar weaves a brown-gray oblong cocoon. The mass migration of butterflies occurs in the second ten days of July and lasts about a month.

Butterflies don't feed. The female lays an average of about 300 eggs, placing them singly or in groups.

During the period between outbreaks, the silkworm does not cause serious damage: its number is 1-2 caterpillars per tree, and caterpillars cannot be found on every tree.

In the dark coniferous taiga, silkworm outbreaks form after several years of hot, dry weather in the summer.

The main danger of an outbreak of the Siberian silkworm is not only that an average of 0.8 million hectares are destroyed annually by the Siberian silkworm, but also that forests destroyed by silkworms are poorly restored. The caterpillars destroy the undergrowth along with the forest stand, and only after a decade is it possible for a small undergrowth of deciduous species to appear. In old foci, conifers appear only 30-40 years after the tree stands dry out, and not everywhere and not always.

Even if the forest is not completely destroyed by silkworms, damaged plantings (“silkworms”) subsequently become hotbeds for forest stem pests, primarily black coniferous longhorned beetles, as well as bark beetles, borers, and horntails. In turn, they can significantly expand the initial zone of forest drying out, moving to completely healthy trees.

Getting worse high-quality composition tree stand.

If you find a Siberian silkworm on the coniferous trees of your site, you must immediately organize measures to combat this pest.

During mass reproduction, coniferous trees should be treated with insecticides. The most effective biological drug at present is lepidocide.

And to prevent Siberian silkworms, it is necessary to regularly inspect trees for the presence of pests and carry out preventive treatment with insect repellents.

To avoid the spread of the Siberian silkworm, Rosselkhoznadzor experts recommend introducing a number of phytosanitary restrictions: when exporting coniferous species, they must be debarked or disinfected in order to prevent the spread of the Siberian silkworm further through the coniferous forests of Russia. There is now increased attention to the export and import of coniferous wood: without the appropriate accompanying certificate, such cargo may be illegal.

If detected, you must contact the Amur branch of the Federal State Budgetary Institution "Trans-Baikal Reference Center of Rosselkhoznadzor" to carry out the necessary processing.

Registration of quarantine phytosanitary documentation for the export of forest products and timber from the territory contaminated with quarantine objects is carried out by the Rosselkhoznadzor Office for Transbaikal region and the Amur region in accordance with Federal law from 07/15/2000

N 99-FZ “On plant quarantine”, Resolution of the Governor of the Amur Region dated 04/13/2009 N 187 “On imposing quarantine on the Siberian silkworm in the Blagoveshchensk region”, as well as the order of the Ministry agriculture Russian Federation dated March 14, 2007 No. 163 “On the organization for issuing phytosanitary certificates and quarantine certificates.” Permits are issued based on the conclusion issued by the Amur branch of the Federal State Budgetary Institution "Trans-Baikal Reference Center of Rosselkhoznadzor" on the quarantine phytosanitary state of regulated products.

The Siberian silkworm is a large butterfly with a wingspan of up to 80 mm (photo below). Males differ from females in their smaller size and the presence of comb-like antennae. The color is yellowish-brown, brown, gray, black. There are patterns and light spots on the front pair of wings. The hind wings are a single color. A photo of the Siberian silkworm at the adult stage is presented below.

The eggs are spherical, up to 2 mm in size (photo below). Initially, the eggs are bluish-green in color, gradually changing color to brown.

Note!
The color may vary depending on where the female laid the egg - on the bark of trees, stems, leaves. Siberian silkworm eggs are located in groups or one at a time. The photo can be seen below. One clutch can contain about 200 pieces.

Siberian silkworm caterpillars are born miniature - about 2 mm. They eat well and grow quickly. At the last stage of development, the body length of the larvae is 70 mm. The color is variable - from green to brown and almost black. You can see stripes on the body purple, spots. Caterpillars go through 4 molts and constantly increase in size. Photos of the butterfly's offspring can be seen below.

At the end of development, the Siberian silkworm caterpillar turns into a pupa. The cocoon is formed from a silk thread, which it produces itself. It clings with its paws to the bark of trees, stems, leaves, and freezes. Cocoon size up to 40 mm. Initially, the covers are light, then they acquire a brown tint, black, which is clearly visible in the photo of the Siberian silkworm cocoon.

Features of development

The butterfly flight begins in the second half of July and lasts about a month. Mating occurs on the fly. The male dies soon after fertilization, the female looks for a favorable place to lay eggs. Attaches them to tree bark and leaves using a special sticky substance that is released along with the eggs.

The larvae inside lasts up to 22 days, with favorable conditions The young offspring of the Siberian silkworm appear already on the 13th day. First instar caterpillars actively feed on needles and grow quickly. During the period from August to September, they increase significantly in size, and the chitinous cover becomes denser. The cycle in the photo. At the end of September, the caterpillars crawl under the bark and forest floor and remain for the winter.

With the onset of warmth - in May, the larvae rise to the crowns, where they live and feed throughout the warm season. The caterpillars undergo the second wintering at the fifth or sixth age. They continue to develop in May and pupate by the end of June. The development of a butterfly in a cocoon lasts about a month. Externally - a motionless creature, inside - the most complex processes of transformation take place. Young butterflies appear in early September. Their task is to find a secluded place for wintering. Below is a photo of the young.

Note!
Development occurs over 2-3 years, while butterflies at the imago stage live no more than a month and do not feed on anything. Energy reserves are enough to lay about 300 eggs at a time.

Sabotage

It’s not hard to guess why the Siberian silkworm is dangerous. Due to the fact that the development of the larvae stretches over several years, and every spring they rise into the crowns, there is a risk of weakening the tree.

Butterflies disperse their numerous offspring throughout different plants. In July, mass infection covers several million hectares of forest. This causes enormous damage to forestry. Natural enemies Siberian silkworms include borers, bark beetles, and longhorned beetles. The photo can be seen below. Since bark beetles also cause damage to coniferous plantations, the scale of the pest increases several times more. Birds of prey eat insects.

In the mid-90s, the fight against Siberian silkworm larvae lasted 4 years. Then about 600 thousand hectares of forest area suffered from the pest invasion. Cedar trees, which were of great value to local residents, died.

Over the past 100 years, 9 outbreaks of mass pest control of silkworm caterpillars have been observed in Siberia. It was possible to stop the reproduction thanks to the use of modern insecticides. and other plants are taken constantly, if not to destroy caterpillars, then to prevent their appearance. Photo mass destruction plants are presented below.

Interesting!
Sericulture is especially developed in China. Natural silk, which is obtained from threads, is highly valued. Insects are specially bred on mulberries, providing everything necessary conditions existence. The cocoons are collected without allowing the butterflies to be born. The length of the threads of one cocoon is about 900 m. Butterflies lead a sedentary lifestyle and practically do not fly. The larvae are not dangerous to surrounding plants.

Fighting methods

Caterpillars damage larch, oak, beech, birch, pine, spruce, aspen, fir, cedar, and maple. prefers deciduous trees, but does not disdain conifers. The first instar larvae feed during the day, and as they grow older they switch to a hidden lifestyle - they crawl out of their shelters at night.

Main control measures:

Collection and destruction of ovipositions. In small areas, young trees are scraped off by hand, trampled underfoot, or thrown into the fire. Below are photos of infected plants.
Late autumn or early spring eggs are destroyed using petroleum products - gasoline, kerosene, motor oil. However, you should always remember that these are flammable substances; if used incorrectly, the risk of a massive fire increases.
Against the larvae, adhesive rings are used, which are placed at a level of 1.5-2 m above the ground surface, which does not allow pests to reach the crown.
In small areas, caterpillars are collected by hand and then destroyed in any way.
Most effective method– insecticidal substances. Spray crowns and tree trunks. Treatment can be carried out in early spring before or after the trees bloom. The effect of the poison lasts for 20-45 days. Repeated processing is carried out as necessary.

Every autumn and spring, you need to carefully inspect the bark of trees for the presence of eggs and larvae, and coat the trunks with a solution of lime and chalk. Life cycle The insect's life spans several years, so there is always a threat of infection. Spread to other trees occurs either in early spring or late autumn. You should carefully examine the pest in the photo so that you can respond to the problem in a timely manner.