What is Hermes, measures to combat the pest of conifers

Coniferous wood is always a decoration of the garden plot, because it looks elegant and spectacular all year round.

Pine, spruce, fir and larch are considered more resistant to disease, compared with deciduous species, but even these plants are subject to attacks by pests.

In this article we will talk about Hermes - one of the most common pests of conifers, because many gardeners do not even know about the existence of Hermes, and do not know what it is.

Hermes - what is this pest?

Hermes (Adelgidae) - a group of insect pests of conifers from the order horned wing, akin to phylloxera and apha. Hermes can give this description: small sucking insect up to 2 mm long, black or dark brown in color, with an oblong body and antennae on the head, looks like an aphid.

Hermes eats the juice of twigs, shoots and needles, sucking it out of young trees. The most susceptible to the attacks of this parasite is spruce and pine. Hermes livelihoods will tell you how to find a pest on a tree: the needles bend and turn yellow; a white bloom or fluff appears on it at the end of spring, as well as on the buds and last year's shoots.

White bloom is nothing more than a fibrous case that covers the Hermes larva. The plant affected by this parasite from June to August has solid galls on the young shoots that look like pineapple, from which scales the needles of pine needles stick out and sometimes tar comes out.

Important! In order to avoid contamination of spruce with Hermes, it should be planted at a distance of not less than 600 m from the nearest larch or fir, thereby the migration phase of reproduction will be destroyed.

Features of the life cycle of Hermes

The life cycle of Hermes is a rather complicated process, which consists of several stages; a cycle can be a year or two long. The duration of the life cycle depends on the type of Hermes.

Also, each species requires either one type of tree or two for its vital activity, but in any case, spruce is always the original plant. Hermes life cycle has a feature - asexual and sexual generations of insects alternate.

Sexually mature female Hermes spawns her spruce or pine in the kidney; under the influence of this liquid, a gall is formed on the shoot, in which the female lays eggs in the fall. Gauls contain fat and starch, the hermes larva is born from the egg, which eats the nutrient content of the gall. In each gall it can simultaneously develop up to 26 larvae, each in its own chamber.

As a rule, only Hermes eggs survive the winter, of which larvae hatch in spring, and then founding females without wings, which are able to reproduce with eggs without the participation of the male. Such reproduction is also called parthenogenetic.

Of the eggs laid by the foundress of the founders during the spring and summer, several winged generations with parthenogenetic reproduction appear. These winged individuals are able to settle on fairly large areas for feeding and reproduction.

Closer to autumn, a wingless generation of females and males is born, as a result of their mating on the spruce, fertilized eggs are laid for the winter. The foundress will emerge from these overwintered eggs in the spring, and the cycle of life and reproduction will be repeated again.

Hermes species such as spruce-fir and spruce-larch, derive several generations, each of which fulfills its mission and, if necessary, flies to another plant, thereby changing the feeding tree, and eventually returns to the spruce, thereby completing the cycle of life . Other species live and breed within the same plant and are often wingless insects.

Did you know? Early breeds of Hermes in June form small oval galls at the ends of branches, late Hermes in late summer-early autumn form large spherical galls.

Common Hermes

Yellow hermes, late spruce hermes, subcortical spruce hermes and spruce-larch hermes are most common.

Hermes Yellow. For a year one generation of insects appears. The female foundress of the yellow hermes sucks the juice from the needles in the axils of the young shoot, as a result of which an elongated gallus 10-25 cm long is formed. The gall is green and its scales have a red border. The escape, in which the gall appeared, is deformed and does not fully develop. After the gall is eaten on the spruce, the female lays in it a multitude of eggs, from which larvae feed on the sap of pine needles inside the gall. In summer, individuals of the next parthenogenetic generation fly out of the gall, which settle on the spruce shoots and continue their life cycle.

Late spruce hermes. Females create spherical pale green galls with prominent scales that were previously needles - prior to the attack on the Hermes spruce pest. Late Hermes chooses for his breeding a spruce bud, which is located at the end of a one-year sprout. The female drinks the sap of the plant, while it produces saliva, which by its composition contributes to the formation of gall. In the fall, eggs for reproduction are laid in the autumn gall; in spring, larvae hatch out in it, which leave the gall in July and settle over the entire area of ​​the plant. Late spruce hermes lives and breeds on the same plant, preferring for this side branches.

Did you know? The white fibrous plaque on the Hermes is externally similar to a thin snow cover, it is necessary for the pest to avoid loss of moisture from the body.

Podkorovy fir hermes. This pest does not use galls for breeding, individuals without wings that live on the bark of the trunk or branches of only one tree - spruce are hatching. It is possible to detect subhermal hermes on a white patina on the bark - these are small pest females covered with a fibrous substance of white color. In this case, the pest affects the European or Siberian spruce.

Spruce-larch, or green hermes. The life cycle of a pest of this species has the most complex reproduction process. Hermes female forms a spherical gall up to 20-30 mm in length, and lays eggs in it. In the summer of the larvae, winged migrants of Hermes hatch, which fly for breeding to larch. These migrants are covered with secretory fibers and similar to the snow cover on the shoots. Hermes' winged individuals feed on larch juice and lay eggs on it. In autumn, larvae emerge from the eggs, which lodge under the larch bark near its buds for wintering.

In the spring of next year, overwintered larvae reborn as false founders, each of which is able to lay up to 200 eggs. A generation of females and males will emerge from the laid eggs, which will fly over to the spruce for laying a new batch of eggs and will stay on it for the winter. Females hatch from these eggs, laying only one egg, which will then give life to one founding female, capable of forming galls. So there is a cyclic reproduction and development of Hermes with the participation of two varieties of trees.

Important! Hermes species such as yellow and spruce-larch affect young spruce trees that grow in dry ground, on a steep slope or lowland; Late Hermes prefer mature spruce plants, which also grow in not very favorable conditions.

How to deal with Hermes on trees

When dealing with Hermes, one should not forget that this is not a disease, but a pest, and it is possible and necessary to get rid of it, like from a parasitizing insect. If Hermes is found on spruce or other conifers, the first thing to do is to cut and burn parts of the shoots with galls, it is advisable to have time to do this in early summer, until the larvae in them have finally developed.

Then in several passes wash the pests from the branches with a stream of water under pressure. After that, you need to spray the tree with a solution of mineral oil - 150 ml per 5 liters of water. If the specified sparing methods were not effective, the plant is treated with Aktara, Confidor, Mospilan or Commander according to the instructions for use.

Did you know? After the Hermes larvae leave the gall, it dries out and remains on the tree for a long time.

Preventive measures: how to increase resistance to pests

The most important prophylactic is do not plant near spruce larch, since the proximity of these plants favorably affects the reproduction of Hermes. Healthy seedlings should be planted in loose and fertile soil, in dark places without drafts.

It is recommended to mulch the soil with pine bark, and the plant can be treated with Eupin, a means to increase immunity, which will provide additional protection for conifer trees from Hermes. Periodic repeated spraying of conifers with “Decis” or “Fastak” preparations will serve as a preventive remedy for Hermes.

Watch the video: Spruce Diseases (January 2020).