California scale insect: description and control methods. How to fight scale insects on plums Californian scale insects methods of control

160

Photo. California scale insect - Quadraspidiotus perniciosus (Comst.)

Systematic position.

Class Insecta, order Homoptera, suborder Coccoidea, family Diaspididae, genus Diaspidiotus Berl. et Leon.

Biological group.

Pests of fruit crops.

Morphology and biology.

The body of an adult female is lemon yellow. It is hidden under a round, dark gray shield with 2 molt skins in the center. The diameter of the shield is 1.5-2 mm. The species is viviparous. During 2 months of life, the female gives birth to up to 150-200 yellowish stray larvae. The body of the hobo is clearly segmented, with a long proboscis, antennae, eyes and 3 pairs of legs. Body length 0.25-3 mm. In unfavorable weather conditions, the strays hide under the female's shield. Having settled, they stick to the plant, their body is covered with fluff, from which a shield is later formed. After 8-12 days, the first moult occurs, as a result of which legs, antennae and eyes are lost. After 2 moults, the larva turns into an adult female. The larval development of the male, in addition to 2 larval instars, also includes the pronymph and nymph stages. Male larvae differ from female larvae in the elongated oval shape of the scutum. The adult male is light orange in color with 2 wings. Its lifespan is only a few hours. Larvae of the 1st instar overwinter. They are distinguished by a larger black shield.

Spreading.

Homeland - Far East of Russia, Northeast China and the north of the Korean Peninsula. Introduced with plants to many countries in Europe, North and South America, Africa, Asia, Australia, Tasmania, New Zealand, and Hawaii. B b. The USSR is found in Moldova, Ukraine, Crimea, the Caucasus, the Amur region, Khabarovsk and Primorsky territories, southern Sakhalin, the Kuril Islands, Kazakhstan, Turkmenistan, Uzbekistan, Tajikistan.

Ecology.

Economic importance.

Internal quarantine facility. Pest of apple, pear, plum, peach, sloe, currant and, to a lesser extent, cherry and quince. Apple harvest losses up to 15-100%. If the infection is severe, cracks appear on the trunk and branches, and the plants do not tolerate frost well. Seedlings usually die 3 years after infection. Affected apple and pear fruits with characteristic numerous red spots. To combat the Californian scale insect, quarantine control and disinfection of planting material are of great importance. Prospaltella perniciosi Town is used in biological control. Pheromone traps are used for monitoring.

© Davidyan G.E.

Latin name:

Quadraspidiotus perniciosus

Synonyms:

Pest scale insect, Diaspidiotus perniciosus, Aspidiotus California, California scale, Chinese scale, Pernicious scale, Aspidiotus perniciosus, Comstockaspis perniciosus, Aonidiella perniciosus, Comstockiella perniciosus, Black pine-leaf scale

Classifier:

Arthropods › Insects › Hemiptera (Homoptera)› Scale insects

Literary sources:

1. Batiashvili I.D. Pests of continental and subtropical fruit crops. Tbilisi: Publishing House Cargo. Agricultural Institute, 1959. 455 p.
2. Borkhsenius N.S. Suborder Coccoidea. Scale insects and scale insects. / Harmful animals of Central Asia (Directory). Ed. E.N. Pavlovsky, A.A. Stackelberg. M.-L.: Publishing house. Academy of Sciences of the USSR, 1949. pp. 231-245.
3. Borkhsenius N.S. Catalog of scale insects (Diaspidoidea) of the world fauna. M.-L.: Nauka, 1966. 449 p.
4. Borkhsenius N.S. Practical identification of coccids (Coccoidea) of cultivated plants and forest species of the USSR. L.: Nauka, 1973. 311 p.
5. Vasilyev V.P. Garden pests. Kyiv: Publishing house. Academy of Sciences of the Ukrainian SSR, 1955. 265 p.
6. Pests of agricultural crops and forests. T. 1. Harmful nematodes, mollusks, arthropods. Ed. V.P. Vasiliev. Kyiv: Harvest, 1973. 496 p.
7. Danzig E.M. Suborder mealybugs, or coccids - Coccinea. / Identifier of harmful and beneficial insects and mites of fruit and berry crops in the USSR. Comp. L.M. Kopaneva. L.: Kolos, 1984. 288 p.
8. Californian scale insect in the USSR. Ed. A.N. Kirichenko. M.-L.: Selkhozgiz, 1937. 272 ​​p.
9. Insects and mites are pests of agricultural crops. Insects with incomplete metamorphosis. Ed. O.L. Kryzhanovsky, E.M. Danzig. T. 1. L.: Nauka, 1972. 323 p.
10. Pilipyuk V.I. Californian scale insect on Sakhalin and the Kuril Islands. Plant protection. N 7. 1971. S. 43-44.
11. Ryabtseva N.I., Shutova N.N. Californian scale insect in the Tajik SSR and measures to combat it. Stalinabad: Tajikgosizdat, 1954. 38 p.
12. Savkovsky P.P. Atlas of pests of fruit and berry crops. Kyiv: Harvest, 1976. 207 p.
13. Smolyannikov V.V. California scale insect - Quadraspidiotus perniciosus (Comst.) in the USSR. / Proceedings of the Central Research Laboratory for Plant Quarantine. Vol. 1: California scale insect - Quadraspidiotus perniciosus (Comst.). M., 1973. S. 1-19.
14. Talitsky V.I. Scale insects and false scale insects are pests of fruit crops in Moldova. Chisinau: Gosizdat, 1954. 46 p.
15. Shutova N.N. Ecological conditions for the existence of the Californian scale insect Quadraspidiotus perniciosus (Comst.) in the USSR. / Proceedings of the Central Research Laboratory for Plant Quarantine. Vol. 1: California scale insect - Quadraspidiotus perniciosus (Comst.). M., 1973. S. 20-27.

- a very harmful insect. After all, it parasitizes one and a half hundred varieties of cultivated plants. In our conditions, the scale insect causes the most damage to fruit trees. Insects can be found on apple trees, cherries, pears, etc. Moreover, this pest affects leaves, branches, and even tree trunks. Naturally, not a single gardener will put up with the destruction of their green spaces. But before discussing how to deal with this pest, it’s worth getting to know it better.

Females

Female individuals lack legs, antennae or wings and have a round shield. The size of the insect is extremely small, usually about 2 millimeters. The shell takes on the color of the plant on which the pest feeds. A characteristic feature is the white border in the center of the shield.

Males

Males are slightly smaller (up to a millimeter), their scutum is oblong. They have a dark crossbar on their shell, and they also have developed wings, antennae and legs, and purple eyes.

Larvae

There are several forms of larvae:

• a vagrant, recently hatched from an egg, up to 0.3 millimeters long. Has eyes, mouth, legs;
• nymph, a transitional stage during the formation of the chitinous shell. The body is oval, the color is black.

Damage caused by insects

Since the Californian scale insect has no natural enemies, the insect reproduces at an impressive rate. It forms large populations on trees that actively suck out plant juices. The consequence of this is cracking and subsequent death of the tree bark.

In most cases, the affected plant either stops bearing fruit at all, or produces fruits of minimal size that are unsuitable for food. Often, even in mild frosts, affected trees die.

Signs of infection

The main sign of scale insects appearing in the garden is the formation of round, brown scales on the leaves that are difficult to separate from the surface. Another sure sign is the loss of tree bark of its natural shine, as well as the appearance of sap drips and gluing of individual leaves.

Preparatory activities

Before using chemicals to disinfest plantings, you should remove fragments of dead bark, dry branches, damaged and dried leaves, root shoots and thin out the crown. All removed parts of plants are collected and necessarily burned.

What actions need to be taken?

The fight against the Californian scale insect is quite difficult, but necessary. All control methods used today should be carried out in the first days of March, until the buds set on the trees. Tying to exactly this time is important, since the larvae overwintering on the bark wake up during this period and begin to feed.

If we list the most effective measures to combat the Californian pest, then the first and main thing should be spraying trees with pyrethroids, neonictionides and other compounds including organophosphorus compounds.

This procedure can even be called not spraying, but washing, since the plants are completely covered with the solution used. This is the only way to guarantee the complete destruction of the larvae and prevent further reproduction of adults. Specific effective remedies include: Aliot, Iskra-M, Inta-VIR, Kinmiks, Fufanon.

In addition to the names of the drugs mentioned above, you should also remember about mineral oils. When they are used to treat trees, an airtight film of micron thickness is formed over their entire surface, preventing the larvae from breathing and contributing to their rapid death. These compounds are safe for people. The good thing about this method is that it can be used even if there are already ripe fruits on the treated plants.

To ensure success, treatment can be repeated at intervals of 5 to 10 days. But you shouldn’t use insecticidal chemicals too often; in this case, you can damage the plants themselves.

To help plants affected by scale insects recover faster, the usual measures are enough - fertilizing, abundant watering, etc.

A typical polyphagous quarantine pest that damages 210 species of fruit, ornamental, shrubs and forest deciduous plants.
In orchards, it most damages apple trees, pear trees, plum trees, cherries, currants, and roses. The first instar larvae of the pest overwinter under scutes 1 mm in diameter on the bark, colored in its color. With the onset of sap flow, the larvae begin to actively feed and increase in size. Further body growth is limited by the scutum, so the first molt occurs. In 10 - 12 days, new scutes of large sizes are formed and division into females and males occurs. In females the shield is round, in males it is oval. The number of males is 10 - 15 times less than females.

The subsequent development of the pest occurs as follows: some of the larvae stop their development and go into biopause; they will remain over the winter in order to continue their genus the next year. The other part, consisting of females and males, will undergo a second moult, the males will fly out of their scutes, live for three to four hours without feeding, fertilize the females and die, and after 25 - 30 days the females will begin to give birth to live larvae - vagrants of 100-150 pieces each . The process of hatching strays is very drawn out and lasts about two months. This makes pest control more difficult. The wanderers are very small, only 0.5 mm long, but very mobile. They wander around the tree from several hours to several days until they find a suitable place. Such a place is usually the tops of trees and the southern side of the crown, places that are well lit and warmed by the sun. By piercing the bark, and sometimes part of the wood, with its proboscis, the tramp begins to feed and switches to a sedentary lifestyle. She builds a shield over herself, under which she will live, develop, give birth to strays and die. This is how the formation of the first generation ends. In our area, the pest develops in two generations. The emergence of tramps occurs in the second ten days of June and August, respectively.

This period, when the pest has come out of its “shelter” and is on the surface, should be used to destroy it. With the onset of frost, part of the pest in different phases of development dies, and in frosts of 30 -35 ° it completely dies. The Californian scale insect is dangerous because it very quickly reproduces. One female in two years can give birth to one million larvae. Spreads mainly with planting material and cuttings. If no control is carried out against it, trees die in 3-4 years. In terms of harmfulness, it ranks first among all pests, Therefore, it is necessary to fight it actively and continuously.
A system of protection against Californian scale insects has been developed, including agrotechnical and chemical methods. Agrotechnical measures are aimed at increasing the resistance of trees to the pest. It has long been noted that weakened plants are more susceptible to pests and diseases than healthy ones. Therefore, fruit and berry plantings need to create all conditions for good development and growth. This includes - watering, fertilizers, pruning, thinning the crown, removing heavily infected trees and shrubs from the site, cutting out root shoots, reducing the crown to a height of 4 - 4.5 m, clearing loose bark on the trunks and skeletal branches, keeping the soil loose and wet condition. Chemical measures include spraying with chemicals. The pest is quite reliably protected by a shield through which pesticides do not penetrate. The most vulnerable period in the life of the pest is the hatching of the strays, when they wander around the tree and have not yet covered themselves with scutes. But, as is known, females give birth to strays within two months, therefore, in order to destroy the strays, it is necessary to spray the plant at least every other day, which is practically impossible. Which exit? There is only one way out - to destroy the pest before its development begins, when it is in the winter phase, that is, in the early spring. This is what they usually do, spraying the dormant buds with oily emulsions. In this case, the emulsion film covers the shield, gas exchange is disrupted, and the pest suffocates. On the other hand, the oil penetrates the shield, enters the body of the scale insect and poisons it.

Hence the practical solution - you need to not just spray, but wash the trees so that the emulsion covers all its parts. Meanwhile, the pest hides under the remaining bark, in cracks, on the root collar.

If timely measures are not taken to combat Californian scale insects, which damage many shrubs, you can lose the harvest, and in the most advanced cases, the plants themselves. The fact is that the bark of damaged trees cracks, first thin and then skeletal branches die. The fight against scale insects should begin in the spring, before the sap begins to flow in the trees, while there is still an opportunity to completely exterminate the pest.

What does the scale insect look like in the photo and how to deal with the pest in the garden

Photos of scale insects and measures to combat them are for your attention on this page:

California scale insect is a dangerous pest of garden crops, damaging many trees and shrubs (apple, pear, peach, plum, hawthorn, quince, and other plants).

An inexperienced gardener, knowing about the need to combat scale insects in the garden, can detect these worst pests on fruits and in the form of small dots with a bright rim around them. These are summer wanderers, and the bulk of the pest is on the bark of trunks, skeletal branches and young shoots in the form of a gray-white solid coating that is easily cleaned off with a fingernail.

Many people, not knowing what the scale insect looks like, think that it is a rather large insect under a brown, convex, clearly visible shield. In fact, this pest is very small, but the damage it causes to plantings is very large.

In damaged trees, the bark cracks and falls off, leaves fall off prematurely, and thin and then individual skeletal branches die. Red spots on fruits sharply reduce their quality, they become smaller, do not gain sugar content, wither and fall off prematurely.

Without taking measures to combat scale insects, if plants are heavily infested, trees and shrubs may die. Affected seedlings dry out after 2-3 years.

Look at the photo what a scale insect looks like - the female pest’s body is round, lemon-yellow in color, covered with a round shield, the size of which is 1.5-2 mm (that’s why they are so difficult to see):

Females are viviparous. Maximum fertility is 130-140 larvae. The larvae are flat, oval, yellowish-lemon. The hatched larvae (vagrants) lead an active lifestyle and move throughout the plant. Then the wanderers, sticking their proboscis, attach to the plant and begin to secrete white waxy threads, from which a white shield is formed that covers their body. Soon the shield becomes light gray, then dark gray. On the 10-12th day after suction, molting occurs and the pest’s body increases in size. The larval skin is attached to the bottom in the center of the scutellum, and the larva enters the second instar.

The scale insect overwinters in the stage of first instar larvae, but in warm winters second instar larvae and adult females are found. Overwintering larvae have a dense black shield.

The awakening of the wintering generation in the spring begins with the beginning of sap flow in the trees. Therefore, the first methods of combating scale insects should be taken already at this stage.

Scale insects live and develop in different climatic conditions, but produce an unequal number of generations. In the southern region - two, on the Black Sea coast of the Caucasus - three, and in the central zone of Russia - one generation.

The pest spreads with planting and grafting material. Vagrants can crawl from tree to tree along interlocking branches.

Colonies of these insects are especially numerous in neglected, unkempt gardens. Where effective methods of controlling California scale insects and other pests (leaf rollers, codling moths, aphids) are not used.

Means and methods of combating Californian scale insects on trees

How to fight scale insects in your garden using effective drugs?

When these insects appear in the garden during the mass hatching of vagrants (mid-June and mid-August), spray the infested trees with one of the insecticides. Good means for combating scale insects are “Aliot”, “Kinmiks”, “Iskra-M”, “Fufanon”, “Inta-VIR”. For greater reliability, the treatment can be repeated at intervals of 5-6 days (for example, June 15 and 20), alternating the pesticides used.

The number of scale insects is also reduced by spring spraying of fruit trees against leaf rollers and weevils (the last ten days of April); at this time the scale insects molt, but the preparations are the same.

Solutions of pesticides should fall on plants in the form of tiny splashes - sprayed.

They must be applied evenly not only to the top, but also to the underside of the sheet.

To achieve high spraying efficiency, you need to ensure that the entire tree and especially the cracks in its bark are well moistened with the solution.

Another effective method of combating scale insects on trees:

Agrotechnical measures aimed at thinning the crowns of infected trees and burning cut branches. Timely fertilization and watering, cleaning dead bark on trunks and skeletal branches, removing dying trees and bushes from the garden, destroying root growth.