Pest Type: Cabbage Pest
It is found everywhere. It damages cabbage, turnips, radishes, rutabaga, spring rape, mustard, and other cabbage.
Beetle 2.5-3.2 mm in size, gray-brown, near the scutellum a white quadrangular spot. The head tube is thin and long, bends under the chest and fits between the coxae of the front legs. Antenna maces are similar. 0.8 mm egg, transparent, oval. Larva-up to 5 mm, yellow-white, with a brown head, without legs, slightly bent. Pupa-4 mm, loose, yellowish.
Immature beetles overwinter under plant debris at the edges, in forest belts, parks, and gardens. Beetles awaken in the first half of April when the temperature of the upper soil layer warms up to 8-9 ° C. First, the beetles additionally feed on wild-growing and later on cultivated (oilseeds, fodder, and vegetable) cabbage plants in the field and seedlings in greenhouses. They gnaw at the stalks and thick veins of the epidermis, and then eat out the flesh in the form of small chambers around which the tissue grows, and bloating “warts” form. Sometimes they bite holes in the leaves and damage the tops of young stems of cabbage seedlings and testes.
In early May, females lay 3-4 eggs in the middle vein of the leaf, less often in the petiole and stem. Fertility is 40-60 eggs. Places of laying eggs by females swell and resemble warts. Larvae that hatch after 4-7 days gnaw through the course of the leaf stalk, and then move down to the middle of the stem, sometimes to the root neck. On large sheets, the development of the larva ends in the cuttings, without going into the stem. The larva moves are clearly visible in the form of brown stripes. In one leaf, 15-20 larvae can develop.
Damaged plants lag behind in growth and often die. On the testes, the leaves die off and fall off, flower-bearing shoots break, the seeds become flat. The development of the larvae is completed in 20-30 days, after which they burrow into the soil, where they pupate in earthen cradles at a depth of 2-3 cm. After 18-20 days, in June-July, beetles emerge, which after a short feeding period migrate to wintering places. Annual generation.
Protective measures. Autumn deep autumnal plowing. Selection of intact seedlings. The destruction of cabbage weeds. When 20% of the plants are populated and one or more beetles are abundant per plant, spraying with an insecticide is recommended. On the testes, spraying is effective at the beginning of budding.