How to detect and destroy a rodent sawfly?

Rosewood sawfly is an insect that actively parasitizes on berry and ornamental crops. It affects pink blossoms, most often rose bushes, for which it got its name. The most harmful are the larvae - these inconspicuous creatures with appetite eat juicy foliage and as a result, after their invasion, only bare branches remain on the bushes. They can also nibble shoots, which is why plants begin to rapidly wither. Is there any salvation from this scourge?

Description

Rosewood sawfly is a small insect with shiny covers, whose body size is from 7 to 10 mm. Sexual demorphism is expressed by the presence of an ovipositor, a pointed end of the body, and a thickened abdomen in females.
As you can see in the photo, the body color of the rodent sawfly is black and yellow: the head, upper legs, legs and chest are black, the wings are translucent webbed with a yellowish tinge. On the head there is a pair of short thick antennae, from where the second (folk) name of this insect appeared - the Tolous.

Preimaginal stages: appearance

The eggs are very small - only 0.5 mm. Painted in yellow and white, the structure is glassy, ​​translucent.

The larva is a false caterpillar. The length of her body when leaving the egg is not more than 4 mm. The integument is white, the body is translucent. Upon reaching an older age, the color begins to be visible on the covers, which, depending on the subspecies of the pest, will consist of various shades. On the sides of the body is covered with warts, along the back in two rows are black spots. The head of the larva is roundish yellowish-brown in color, eyes black. There are 11 pairs of legs, three of which are pectoral, the remaining eight are abdominal (false).

The color of the pupa is yellow-white. It is motionless and resides in a two-layer cobwebby cocoon of light brown color. Its outer layer is very fragile, cellular, the inner one is quite dense. Length is about 10 mm, width not more than 5 mm.

Life cycle

The cut sawfly years fall in the warmest season - it begins in May and ends in July. Fertility of females is not more than 70 eggs.

1. Laying is done in 2-3 stages. The female carefully puts each batch of eggs into cuts under the bark of uncut shoots - in this section the shoot is bent, and after the larvae emerge from the eggs, a cavity in the form of a chain with the remaining shells can be found here. Embryonic development takes 9-11 days.
2. Larvae emerge from the eggs in early April; they do not do this at the same time - this process can last from 1 to 3 days. The larval phase involves four molt, and during this time the development of the false caterpillar occurs at five ages. The total duration of the stage is about four weeks. Young larvae live in groups and are located on the lower part of the leaf plate or inside the shoot. Growing up, they gradually spread over the body of the plant, and when they reach the last age, they begin to sink into the soil, where they turn into a two-layer cocoon and spend the winter.
3. In spring, when April heat is stable, in the wintering places pupation of autumn generation occurs, and rosaceae sawflies stay in this phase for 14 days.

On a note! Pupation of pupae can occur both in the stems of plants on which the larval stage proceeded, and in the ground under fallen leaves. Sometimes for pupation, a rooted sawfly chooses cracks in tree trunks and other secluded places!

On average, growing up takes about a month. In the southern regions, where the conditions for the normal life of the rodent sawfly are most favorable, three generations may appear in a year.

Malware

The rosacea sawfly is a pest of the Rosaceae, with the larvae causing the main damage. Adults do not eat at all, after leaving the cocoon they immediately begin to increase the population size - they mate and multiply.

False caterpillars strongly eat strawberry leaves, both garden and forest, damage strawberries, rose hips and garden roses. Younger larvae leave patterns only on foliage, growing up, they gnaw out more extensive areas. As a result, holes of various sizes form on the leaves.

The larvae also spoil the stem of the host plant. Depending on the subspecies, parasites descend or ascend the shoots - descending and ascending sawfly, respectively. The larva of a descending rosacea sawfly gnaws a cavity in the stem, as a result of which the shoots begin to darken and fade. Ascending false caterpillars move mainly along the lower surfaces of leaf blades.

A plant affected by a rosacea sawfly can be recognized by the following signs:

• the plant suddenly begins to wilt, while the tender young top usually suffers first;
• small holes appear on the leaves, which become larger with time;
• the shoots gradually dry up, but this process does not begin from the base, but from a certain place, and if you make a break here, you can find a cavity - a move made by the larvae.

Thus, striking roses, the rosacea sawfly causes huge losses to gardeners, eating rose hips, it significantly reduces its productivity and, in parallel, negatively affects the quality of medicines and cosmetics that will be subsequently made from it.

Methods of struggle

The struggle with the rodent sawfly is complicated by the fact that, being at the most harmful stage of its development, the parasite is inside the shoot and goes unnoticed. After, at the time of pupation, he finds himself in the soil, where he successfully hides from contact insecticides. A positive result can be obtained here if you "catch" the moment the parasite exits the chrysalis by treating the infected bushes at this time. It is most effective to conduct these events in early spring, as soon as the first buds are tied. What can be used?

• Inta-Vir is an intestinal contact insecticide. It is used as follows: mix 1 tablet of the drug with 75 g of malathion and dilute everything in ten liters of water.
• "Actellik" is a non-systemic organophosphorus insect acaricide. To combat the rosacea sawfly, dilute 15 ml of this product in a bucket of water.
• "Aktara" is a systemic insecticide of intestinal contact action. 8 g of the drug is diluted in 10 l of warm water and used to spray infected bushes in the garden.

With the constant use of organophosphorus preparations to combat the rosaceae sawfly, it should be remembered that this parasite is able to quickly acquire group resistance. Therefore, when protecting plants, it is necessary to try to prevent the development of resistance, using insecticides with a different principle of action for this!

However, spraying alone is not a guarantee that the sawfly cutter will be completely destroyed or permanently expelled from the site. This event is only one of the stages.Mandatory additional measures to combat the rodent sawfly are as follows:

• Timely watering and top dressing of plants - thanks to this technique, the bushes will not only develop better, but will also become much less sensitive to pest attacks.
• Regularly inspect the rose bushes and immediately remove the found damaged or dried shoots - it is better to simply burn them outside the site. So you will not allow the spread of the parasite to other parts of plants and neighboring bushes.
• If there are few sawflies, then you can get rid of them with the help of a folk remedy - a decoction of wormwood. To do this, you should brew 300 g of wormwood in two liters of water, and then dilute the broth in a bucket of water. Add 40 g of soap to the product and use on infected beds.

In addition, every autumn, the garden should be dug up and immediately cleaned of fallen leaves and cut stems. Thanks to careful loosening of the soil and harvesting, it is possible to significantly reduce the number of sawfly larvae that settled in the winter hut.