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The most dangerous pest for conifers can rightfully be called the pine sawfly - an insect that can cause colossal damage to a plant or even destroy it.
Scots pines suffer most from the pest, especially at the age of 20-40, however, ornamental plant species are often susceptible to massive insect attacks.
In order to protect coniferous plantations and take all the necessary preventive measures and combat the sawfly, you need to figure out who exactly you are dealing with.
The body color of the false caterpillar of this insect species varies pale yellow to green... On the abdomen of the larva there are black spots located above each false pedicle, of which there are from 18 to 22. The head is shiny, round, brown or dark brown. The length of the false caterpillar reaches 25 mm.
Growing up of a female the common sawfly occurs in 6 stages, while the male goes through 5 instars. The female of an adult insect has a convex body of color from light yellow to red. There are black spots around the perimeter. Antennae are saw-shaped. The size of the female does not exceed 10 mm.
Male color usually black or dark brown, tarsus red. The size of the male is slightly smaller (6-8 mm). Antennae strongly combed.
The body of the red sawfly larva has light gray color... A white stripe is visible along the back, on the sides above each leg there are black spots with a light speck. The head is round, shiny, black. The size of the false track does not exceed 25 mm.
The external data of adults of both species are the same.
Interesting: As a rule, the development of larvae is a long process that lasts several months. In a toga, a false caterpillar pupates in the crown of a tree and after 2 weeks an adult is born. But it happens that the caterpillar goes down to the ground and disguises itself in the grass, fallen needles, hibernating. In this form, the larva can be without food for 24 months.
During the beginning of spring, the larvae of the pest feed on old pine needles. Further, insects move on to younger shoots, causing damage not only to needles, but also to thin twigs.
The larvae "act" in groups, eating the needles, leaving only stumps. One false caterpillar is capable of destroying up to 40 needles.
What harm is done?
Coniferous plantings are harmed not only by larvae, but also by adult pests, which also eat needles. After the first ones eat the needles, it dries up, turns yellow and then falls off.
In the case when there is not enough food, the insect eats up the bark and young shoots, which leads to the death of branches in the crown. Over time, the plant loses strength, becomes sick and, as a result, dies. If a pine sawfly attacked a young pine, it will inevitably die within 3-4 years.
Due to the weakening of the plant, it becomes an easy prey for other pests and is susceptible to many diseases.
The difference between the pine sawfly and other species
It should be noted that outbreaks of reproduction in a specific localization are more typical for this pest, but it happens that reproduction occurs over large areas.
The pine sawfly gives 2 generations a year - in the last weeks of spring and in the middle of summer. An increase in the number of this species is favored by an increase in the ambient temperature - the higher, the faster the development takes place.
If we add a decrease in air humidity to the temperature factor, the conditions become ideal for the development of insect resistance to various harmful influences for it.
If such conditions persist for 2 years, the reproduction of the pest takes on a scale such that all plants around it are susceptible to its attack.
For we present to your attention a photo of pine sawflies:
Read about the variety of sawfly species here.
In coniferous forests, it is quite difficult to defeat a pest, but nevertheless, some control methods exist, and they can help get rid of a harmful insect.
You can create such a ring by applying glue to the bottom of the tree trunk. During the period when the larvae begin to descend in order to form a cocoon, they will fall into the created trap and soon perish. In addition, the glue trap prevents the larvae from climbing up the trunk to the crown of the tree.
Important: the glue must be moisture resistant and not dry out!
Spraying with chemicals
Spraying with chemicals should be applied not only to the affected trees, but also to those standing nearby.
If the insect was found in the backyard, then the fight against the pest must be started as early as possible.
The destruction methods are as follows:
- Planting tomato bushes next to the affected plant, which produce certain enzymes that repel insects.
- Digging in the affected plant, which makes it impossible for the insect to move to another tree.
- Spraying the plant with tincture of mustard, wormwood, tobacco.
- Use of special biological agents to destroy the pest.
- Manual collection of sawfly larvae.
Important: If the pine tree is small and you decide to collect the larvae by hand, be sure to use protective equipment - gloves and goggles. This is necessary in order to prevent the insect's blood from getting on the skin and mucous membranes, which it regurgitates if it feels danger. This discharge can cause a serious allergic reaction.
It is possible to fight the pest, but control measures cannot always give a positive result. Each method is good only at a certain stage in the development of the insect, so the best option would be to simply prevent the appearance of the sawfly.
There are several preventive measures for this:
- The spread of the pest directly depends on the weather. If the forecast for late spring - early summer promises dry and sultry weather, then the appearance of the sawfly on the trees is 85% guaranteed. In small areas of coniferous plantations, it is necessary to provide increased humidity, at which the larvae of the pest die.
- If possible, the best option would be to plant mixed forests (deciduous and coniferous). The presence of bushes in the forest prevents adult insects from finding food.
- The main enemy of this dangerous pest is the bird. Attract as many birds as possible by feeding them and building shelter for them.
Pine sawfly - a harmful insect that can destroy forests in a matter of years. Neglecting methods of prevention, not taking measures to combat a dangerous pest, coniferous plantations are doomed to imminent extinction.
To summarize, we bring to your attention a video about pine sawfires: