Pine sawfly is a dangerous enemy for all types of conifers. It lives in forests where similar tree species are found. It spreads quickly, is able to hit a large area of forest. Insects do tremendous damage to trees.
They are found not only in Russia (the European part, Siberia, the Caucasus), but also in Japan and other Asian countries. Even in North America, outbreaks were observed when the bug hit vast areas of conifers. The place where the insect has never been found is the Arctic.
What does a pest larva look like?
There are several types of such insects:
common sawfly;
red pine sawfly.
Despite external differences, insects cause the same damage, as they have identical habits. The only difference is breeding. An ordinary sawfly gives at least two generations during the summer season, thereby doing more harm.
To make sure exactly what kind of insect harms the tree, you need to know what an ordinary pine sawfly looks like. In size, the larva is not more than 2.5 centimeters. Color can vary from light yellow to green. The head is brown. There is a false pair of legs, indicated by black spots.
The larvae of the red sawfly are distinguished by the color of the body and head. They have a light gray tint with a characteristic white stripe along the back, black spots with light spots are visible on the sides. The head is shiny, black.
The appearance of an adult
The appearance of adult insects of both species of sawflies is almost identical. There are only differences between the female and the male.
The female has a light yellow, sometimes reddish color of the body. Black spots are located around the perimeter. The size is small, the length does not exceed 1 centimeter.
The appearance of the female sawfly is very similar to the chrysalis of this insect. It is in a cocoon of the same yellow color, and the length is not more than one centimeter.
Males are painted black, except for paws (a red tint). The mustache in its shape resembles the crest of a wave.
How does a harmful insect appear?
Female beetles lay eggs in a special way, as if cutting through the needles. Thus, the eggs immediately fall into the soft tissue of the tree. If you look closely, then on the pine trees affected by this pest, you can see convex swellings (galls).
Depending on climatic conditions, in mid-April-early May, larvae emerge from the eggs, which begin to destroy young needles on the sides, and adults eat them whole. They are kept in packs, crawling from one branch to another. Scientists have calculated that one larva is able to completely destroy up to 40 pine needles.
The development of larvae takes a long time and includes 6 stages. On average, they mature within a few months, then pupate in the branches of a tree, and after 15 days a pine sawfly appears.
But this does not always happen. Very often, caterpillars descend the trunk into a bed of grass, moss, and fallen needles. Carefully camouflaged in it and immersed in hibernation. The larva can remain in this state for up to 2 years, while additional nutrition is not required for it. Some individuals can hide in the bark of a tree at its base.
What damage does the pest do?
Forestries in which coniferous trees are planted are familiar with the term "pine sawfly." The measures to combat it are different, the main thing is to detect the problem in time, otherwise the damage from the insect can be huge.
Damage is caused both by larvae and adults. Even if the first eat around the needles on the sides, leaving the middle untouched, it dries up, turns yellow and falls over time. In addition, adult caterpillars eat it whole, and if there is a lack of nutrition, they can reach the bark and young shoots. And this already leads to the fact that the branches in the crown dry out. After a while, the plant weakens, begins to hurt, which leads to the death of the tree.
If a pine sawfly reaches a young pine, then it dies within 4 years. It often happens that in addition to the insect described, a weak tree is attacked by other pests. In this case, the pine tree dies during wintering.
Pine sawfly: how to fight and win in the forests
In coniferous forests it is very problematic to deal with this kind of pest. But still there are methods for getting rid of the insect:
The use of special adhesive rings. A thin layer of glue is applied to the lower part of the trunk, which is not subject to drying and is resistant to moisture. During the period when the larvae go down to form a cocoon, they fall into the created trap.
Chemical spraying of infected and nearby trees.
If the lesion area is large, aerial processing is carried out.
The use of a viral preparation ("Virin-diprion"). When using it, the pH of the medium should be considered.
Dangerous pine sawfly: pest control measures in a personal plot
If you find this evil pest in the country, you need to save the trees. The fight will be as follows:
Planting tomato bushes next to an infected pine bush. The enzymes produced by this plant repel insects.
Digging in an infected tree.
Before planting a young pine, it is recommended to fill in a hole in a specially prepared solution of ash with water.
Spraying with tincture of mustard, tomatoes, wormwood, tobacco.
The use of biological products.
If the pine is small, collect the larvae by hand. Be sure to use gloves and glasses. In case of danger, the insect burps its blood, which can cause a person to have a strong allergic reaction.
Prevention methods
If at least one tree in the forest has been struck by a pine sawfly, control methods should be taken immediately. But they do not always have the desired effect. Each method is good for use at a specific time (larval maturation, pupal formation, breeding season, and more). Therefore, it is better to prevent the appearance of a harmful insect. For this, there are special preventive measures:
In many respects, favorable weather contributes to the spread of the pine sawfly. If weather forecasters predict hot and dry May and June, with a confidence of 80%, we can say that the trees will face an invasion of the pest. If during these months there will be enough rain, you can not worry about the pine trees. At high humidity, the insect larvae die.
If possible, it is better to plant mixed forests (coniferous and deciduous). The presence of shrubs complicates the search for food for adults.
Pine sawfly is a tidbit for birds. Build birdhouses, provide lure for birds, which are the natural orderlies of forests.
Pine sawfly multiplies rapidly and affects a large number of trees. It is necessary to deal with it in order to prevent the extinction of forests.