Pine silkworm is a gluttonous caterpillar that can cause irreparable damage not only on a personal plot, but also in a large forestry. This insect gives particular preference to pines, but can feast on cedar and other representatives of the genus of conifers. To date, there are several really effective methods that can overcome the pest and save trees.
Appearance
Pine silkworm or cocoonworm is a large-sized butterfly and caterpillar. It is a representative of the Lepidoptera order from the cocoon-worm family.
The color of the insect is changeable, from gray, brown to brown. In general, the color of the butterfly is as reminiscent of pine bark as possible. On the upper wings of all individuals there are brown-red stripes, with a jagged black border. And closer to the head there is a white spot on each wing. The body with the lower wings are plain.
Males are somewhat smaller than females, they have a wingspan of 7 centimeters, while females have 9. Another difference is that females have a filiform mustache, while males are combed.
The difference between the pine cutworm and the Siberian silkworm
These two types of insects have many characteristics, and most importantly, both species eat pine. However, the pine cutworm prefers young growth and is a nocturnal inhabitant. The color of the scoop is also different: their wings are brownish-green, reddish, that is, they are most suitable for the color of young bud shoots. At the caterpillar stage, the color of the insect is green, with five white stripes and one white stripe above the legs. Butterfly years begin at the same time as the Siberian silkworm.
Geography of distribution
Pine silkworm is present wherever pines grow. On the territory of Russia, a huge accumulation of insects can be observed along the banks of the Northern Donets, in the ribbon forests of Western Siberia. In the 50-60s of the last century, there were even protracted outbreaks of mass reproduction of the pest. The death of a pine forest from an insect is periodically observed in the Bryansk and Gomel regions.
Cocoonworm prefers plants of middle age. In places where it is very humid, it often dies from fungal diseases, therefore it prefers dry forests.
Reproduction
The summer of butterflies falls in mid-June and ends around mid-August. Already in the middle of the first month of summer, females begin laying eggs. They can be found on pine bark, branches, needles. One female is able to lay about 300 eggs, in one heap of about 50 pieces.
Egg development lasts from 14 to25 days and already in early August, young caterpillars appear, which, having matured, reach 8 centimeters in length. A distinctive feature of the cocoonworm at this stage is a reddish tint on the hairline and dark blue stripes on the second and third segments of the body. Thanks to this, perhaps everyone will recognize the pine silkworm in the photo, as well as seeing it with their own eyes.
Nutrition and Development
Already on the second day from birth, the caterpillar begins to actively eat needles. By mid-autumn, insects descend to the ground and hide under fallen branches and needles. Some individuals even burrow into the ground, about 10 centimeters.
Already with the first spring warming, caterpillars climb onto pine trees and begin to actively devour them, preferring young shoots. However, the insect is usually found on older trees, from 10 years old. Only by mid-June does the insect turn into a chrysalis. During this period of time, a huge number of pupae can be observed on the branches. And after about three weeks, butterflies begin to appear.
In most pine silkworm caterpillars winter one season. But some individuals do not have time to fully develop and hibernate for two seasons.
Harm
The cocoonworm, like most insects, along with harm, has a certain benefit. First of all, the insect eats the old needles of diseased trees, and only with a huge population moves to the young.
One adult is able to eat 60 needles per day, if counted for the entire period before pupation, it turns out more than 1 thousand pieces. Naturally, the trees simply do not have time to recover if there is a huge population of cocoonworms in the region. During a drought, insects are able to absorb hectares of forests, because it is drought that is the most favorable factor for reproduction and growth.
An interesting fact is that in the same region, massive outbreaks of population growth can be observed for 5 years in a row.
Danger to humans
Butterflies do not pose any danger to humans, but the situation is different with caterpillars.
Common pine and marching silkworms in their caterpillar stage have hairs that contain toxic substances. The poison is contained in minimal doses and is designed to protect the caterpillar from insects and birds. However, it can also cause trouble for a person. Naturally, it is impossible to poison yourself with poison from caterpillar hairs, but it strongly irritates the mucous membranes and skin. Therefore, it is strongly not recommended to pick up a cocoonworm at the caterpillar stage.
Natural enemies
The main enemy of the cocoonworm is the egg-eater. The larvae of this parasite develop in silkworm eggs. Butterflies themselves carry this parasite on their body to the places of masonry. The egg-eater itself, being an adult, barely reaches 1.7 mm in size.
Rider flies and tahini feast on silkworm eggs. Eggs are consumed by hedgehogs and shrews. Muscardines are fungi that kill silkworms.
Methods of struggle
If a small population of pine silkworm is found, thenthis place is isolated from other trees, grooves break through, thereby preventing pests from moving to he althy trees. Affected and isolated trees are treated with caterpillar glue. If there has been a mass infection in large areas, then they carry out sanitization with dust using aviation equipment.
Toxic belts give good results. The procedure is carried out at the end of March before the caterpillars begin to wake up before wintering. The essence of the treatment is that the stem of the plant is treated with dust to a height of about 1.2-1.5 meters from the ground.
Additional resettlement of natural enemies can be attributed to additional biological methods of cocoon moth control. Good results can be achieved by adding a telenomus egg-eater. At the same time, telenomus spreads quite quickly, if several individuals of the pest are placed on one masonry, then in just a couple of days the pest will already spread to 300 meters.
In some cases, ants from the genus forminka are settled, which are also a natural enemy of the silkworm. The ant is under protection, so its artificial resettlement is justified.
On personal plots, you can process pine trees with dust, or use special tools, for example, Karbofos.
