How to distinguish a California scale insect and get rid of a malicious pest

Californian scale insect is a multinucleated quarantine pest that damages more than 150 crops, including decorative, garden, and forest ones. If timely measures to destroy are not taken, then one can remain not only without a crop, but also without the plants themselves.

Biological features of the pest

The family of scale insects has more than 2,400 species. A characteristic feature of pests is the presence of a wax carapace-shield, which predetermined the general name. Leadership in harmfulness belongs to the Californian scale insect, which causes damage to both large agricultural enterprises and the owners of household plots.

How to recognize a garden pest

Most often, the Californian scale insects lives on apples, pears, plum trees. Cherry, apricots, cherries, acacia, willow, peaches, rose bushes do not bypass their attention.

Adult insect is characterized by miniature size and protective color. Pests have pronounced sexual dimorphism:

• In the female, the head and chest are merged into a single whole - the cephalothorax. Females lack wings, antennae, legs, and even eyes. The shield is almost round, its size reaches 2 mm in diameter. The color corresponds to the plant on which the Californian scale insect lives, and also depends on the age of the individual. The center of the flap is adorned with 2 rust-brown skins bordered by a narrowly white stripe. The body itself is a bright lemon color, its length does not exceed 1.3 mm.
  
• Males are smaller than females, but on the other hand they have a well-developed pair of wings, antennae, legs and eyes of a deep purple-red color. The oral organ is absent. Male individuals grow no more than 0.85 mm. The body is yellow or brown. The scutellum is painted in light gray, yellow, brown tones, a dark transverse strip passes through the center. The carapace is 1 mm long and half as wide.

Larvae of the first age are called strollers. They differ in well-developed legs, the presence of eyes. Dimensions 0.2-0.3 mm. You can notice them only thanks to the bright yellow or orange color. Interestingly, the oral apparatus in young individuals is twice the length of their body.

Larvae of the second and subsequent ages acquire characteristic features of adult individuals. In males, the shield becomes oval oblong, there is a clear separation of the body into the chest, head, and wings appear. In females, eyes and legs are reduced.

The nuances of life

In the photo, the California scale insect looks like growths on the bark. Single individuals are extremely rare, they mainly live in colonies in which insects of different ages. Winter is spent at the stage of larvae of the first age under the bark of trees.

On a note! California Scalp is resistant to low temperatures. Death occurs only in severe winters, when the thermometer drops below minus 35 ° С.

With the awakening of plants, scales also wake up. Larvae begin to feed intensively and grow in size.The scutellum becomes small and the first molt occurs, after which sexual symptoms appear. The population is dominated by females, the number of males is from 10 to 15%. Further development takes place in two scenarios:

• In one part of the larvae diapause occurs. The carapace of such individuals is black and they go into hibernation until next year.
• Other young individuals continue their development. After completing the males, the males fly out from under the guards, perform their direct duties - they fertilize the females. They do not live long, because they are deprived of a mouth organ and exist due to accumulated nutrients during the larval stage. 3-4 days after the start of summer, they die. Some males have a life expectancy of several hours. Mating usually occurs at the beginning of the second decade of May.

California scale insects are viviparous species. Fertilized females for 2 months engaged in hatching of strollers. Such a long period of reproduction of offspring greatly complicates the fight against the pest. Strollers are very mobile and carefully choose their habitat. Without nutrition, the younger generation is able to live 7 days. They can crawl through the tree for several days until they find a comfortable environment: a well-lit place near the top of the tree, on the trunk, and skeletal branches.

On a note! Californian scale insects on young shoots do not justify a large colony.

Having decided on the habitat, the vagrant with the help of sharp bristles of the oral apparatus pierces the bark. Attached to the plant, it secures wax-like filaments that intertwine and form a white shield, covering the larva from above. After a week, it turns gray. With the onset of this moment, the vagrant sheds and begins a new phase of its development.

What harm does the California scale shield

For humans, the Californian scale insect is not dangerous. Its harmfulness consists in spoilage of fruit plants and rapid reproduction. In the post-Soviet territory, 2 generations of pests appear in a year. The fertility of each female is from 120 to 400 individuals. According to experts, one female increases the population over the year by 500 thousand larvae.

California shields are not characterized by sprinting abilities and they cannot overcome long distances. The spread of the pest occurs mainly through seedlings.

The main signs of the appearance of scale insects:

• the formation of yellow and brown scales on the foliage, it is difficult to separate them from the surface to which they are attached;
• the bark loses its natural luster;
• the appearance of drips of juices on the branches, trunks of fruit trees;
• bonding sheet mass.

Settling in numerous colonies, scabies deprive plants of nutritious juices, which leads to depletion of the plantation, dying of the bark, drying out, deformation of the fruit, and a decrease or complete absence of the crop. If you do not take any measures to combat the Californian scale, the plants die quickly.

How to get rid of a pest

The fight against the California scale insect is a laborious process involving a series of measures:

1. Pruning, thinning the crown of trees, peeling trunks and stems from dead bark, mosses and lichens, timely removal of dry and diseased branches, basal shoots. All cleaning, trimming are subject to burning.
2. The release of chylocorus beetles into gardens in early May reduces the number of Californian scale insects by 50-70%. Each adult beetle eats up to 700 larvae. From biological methods, the resettlement of Perniciosi prosaltella is also effective. The infected scale insects die in the adult stage, her body swells, becomes light in color, and through the cover you can see the parasite itself. To kill pests, drugs based on fungi and pathogenic nematodes are successfully used: Avertin, Nemabakt, Aversectin.
3. Chemical spraying of trees is carried out taking into account the development cycle of Californian scale insects. The greatest effect is achieved when the scabbard is in the wandering stage. Adult individuals are reliably protected by a shield and the use of insecticides against them is impractical.

Chemical control measures for Californian scale insects include early spraying in early March before buds open. This will destroy the wintering larvae and prevent their reproduction and distribution. During processing, it is necessary to ensure that the bark and branches are abundantly moistened with a solution.

For early spraying, “30 V Preparation” is recommended. It is based on mineral oils, which cover the trunks and branches of trees with a thin film, thereby disrupting the air and water balance of scutes, which leads to their death.

In case of severe infections, insecticide treatment is carried out at the end of flowering. The procedure is repeated in June, when a new generation of strollers appears. For spraying use "Karbofos", "Sumition", "Fufanon", "Pirinex".

Alternative methods are effective only with a small number of California scale insects and can be used in the early stages of infection:

• you can try to remove pests from the leaves with a swab dipped in a soap or alcohol solution;
• spraying trees with infusions of garlic, wormwood, walnut, tobacco;
• processing with a mixture of coniferous concentrate 1%, a solution of green soap and brine;
• Spraying with a solution of machine oil and soapy water. The components are mixed in a proportion of 1:10, processing is carried out once a decade.