Pine sawfly is a dangerous enemy for all types of coniferous trees. It lives in forests where similar tree species are found. It spreads quickly, capable of infecting a large area of forests. Insects cause great damage to trees.
Found not only in Russia (European part, Siberia, Caucasus), but also in Japan and other Asian countries. Even in North America, outbreaks have been observed with the beetle infesting vast areas of coniferous trees. The place where an insect has never been found is the Arctic.
What does a pest larva look like?
There are several types of similar insects:
- common sawfly;
- red pine sawfly.
Despite external differences, insects cause the same damage, as they have identical habits. The only difference is reproduction. The common sawfly gives at least two generations during the summer season, thus it can cause more damage.
To be sure which insect harms a tree, you need to know what it looks likecommon pine sawfly. The size of 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 differ in the color of the body and head. They have a light gray hue with a characteristic white stripe along the back, black spots with light patches are visible on the sides. The head is shiny, black.
Appearance of an adult
The appearance of adult insects of both sawfly species is almost identical. There are only differences between the female and the male.
The female has a light yellow, sometimes reddish body color. There are black spots around the entire 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. She is in a cocoon of the same yellow color, and the length is no more than one centimeter.
Males are black, except for the paws (red shade). The mustache is shaped like a wave crest.
How does a harmful insect appear?
Female beetles lay their eggs in a special way, as if cutting through the needles. Thus, the eggs immediately fall into the soft tissues of the tree. If you look closely, you can see convex swellings (galls) on pine trees affected by this pest.
Depending on climatic conditions in mid-April-At the beginning of May, larvae appear from the eggs, which begin to destroy the young needles on the sides, and adults eat it whole. They keep in flocks, crawling from one branch to another. Scientists have calculated that one larva can completely destroy up to 40 needles on a pine tree.
The development of larvae takes a long time and includes 6 stages. On average, they mature for several months, then pupate in the branches of a tree, and after 15 days, the common pine sawfly is born.
But this is not always the case. Very often, caterpillars descend along the trunk into a litter of grass, moss, and fallen needles. They carefully disguise themselves in it and plunge into hibernation. The larva can stay in this state for up to 2 years, while it does not require additional nutrition. Some individuals may hide in the bark of a tree at its base.
What damage does the pest cause?
Forestries planted with coniferous trees are familiar with the term "pine sawfly". 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.
Harm caused by both larvae and adults. Even if the first eat the needles on the sides, leaving the middle intact, it shrinks, turns yellow and falls off over time. In addition, adult caterpillars eat it whole, and if there is a lack of nutrition, they can get to 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 the pine sawflygot to a young pine, then it dies within 4 years. It often happens that in addition to the described insect, 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 woodlands
In coniferous forests it is very problematic to deal with this kind of pest. But still there are methods of getting rid of the insect:
- Using 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 descend to form a cocoon, they fall into the created trap.
- Chemical spraying of infected and nearby trees.
- If the affected area is large, aerial treatment is carried out.
- The use of a viral drug ("Virin-Diprion"). When using it, the pH of the medium should be taken into account.
Dangerous pine sawfly: pest control measures in the backyard
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 the infected pine. Enzymes produced by this plant repel insects.
- Digging up an infected tree.
- Before planting a young pine, it is recommended to pour a specially prepared solution of ash with water into the hole.
- Sprinkling with a tincture of mustard, tomato, wormwood, tobacco.
- Use of biological products.
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If the pine is small, pick the larvae by hand. Be sure to use gloves and goggles when doing this. In case of danger, the insect burps its blood, which can cause a severe allergic reaction in humans.
pine sawfly control methods
Prevention methods
If at least one tree in the forest area is struck by a pine sawfly, control methods must be taken immediately. But they do not always have the desired effect. Each method is good for use at a certain time (larval maturation, pupal formation, breeding season, etc.). Therefore, it is better not to allow the appearance of a harmful insect at all. There are special preventive measures for this:
- In many ways, favorable weather contributes to the spread of the pine sawfly. If weather forecasters predict hot and dry May and June, we can say with 80% confidence that the trees will face a pest invasion. If there is enough rain during these months, you can not worry about the pines. At high humidity, insect larvae die.
- If possible, it is better to plant mixed forests (coniferous and deciduous). The presence of shrubs makes it difficult for adults to find food.
- Pine sawfly is a tasty morsel for birds. Build birdhouses, provide food for birds that are the natural orderlies of forests.
The pine sawfly breeds rapidly and infects a large number of trees. It is necessary to fight it in order to prevent the extinction of forest tracts.
