Pest Type: Sugar Beet Pest
Family: leaf beetles-Chrysomelidae
It is found everywhere. It damages sugar beets, quinoa, white quinoa, kaluzhnitsa.
Beetle 6-7 mm in size; rusty brown on top, sometimes brownish-green with black spots on elytra; margins of pronotum and elytra strongly flattened; bottom black. Egg – 0.4-0.5 mm, oval, light yellow, covered with mucus from above, which solidifies in the form of a transparent film.
Larva 7-8 mm, yellowish-green with a reddish head; flat and wide, with 17 pairs of serrated spiky outgrowths, of which the posterior long, posterior end of the body of the larva keeps it slightly raised and wears skins on it after molting and excrement. A pupa 6.5 mm in size, bright green, flat, with five serrated lobes on the sides, with a dark long strip on the back and two yellow stripes on the sides.
Half-ripened beetles overwinter in plant litter, often in thickets and sparse tree stands. The emergence of beetles from wintering sites is observed in April. In the warm hours of the day, beetles fly to the places of concentration — areas overgrown with weeds (quinoa, white gauze), where they feed. With an increase in temperature and in insufficient humidity, beetles in a significant amount gather in the swamps, damaging the milk worms. On the fifth or eighth day after the start of additional feeding, the beetle’s mate.
Lay eggs on the lower and upper surfaces of the leaf with characteristic heaps, 8-20 eggs each, and fill them with rapidly hardening mucus, which soon turns into a yellowish translucent film. Egg-laying lasts 14-20 days. Fertility is 150-210 eggs. Embryonic development is completed in 4-6 days.
Larvae are born in the second half of May-early June. Depending on weather conditions, the development of larvae lasts from 15 to 30 days, passing five periods during this time. Larvae pupate openly on a leaf of fodder plants. The larva attaches to the leaf with the rear end of the body, discards the molted skin and turns into a pupa. The duration of pupal development lasts 8-12 days.
In the forest-steppe and steppe of Russia, the appearance of beetles is observed in the second half of June and early July. For 12-16 days, they actively eat on plants, after which they mate and lay eggs. Larvae of the second generation feed on beets and, having completed development, pupate in the second half of August. After 10-12 days of additional food (in September) they migrate to wintering places. Beetles and larvae do harm. Younger larvae eat out ulcers on the leaves. Beetles and larvae of older ages gnaw through holes in the leaves.
The number of shield bugs is reduced by carnivorous bugs, larvae of flies, eggs infect chalcid, and eulophids parasitize on larvae and pupae.
Protective measures. Destruction of weeds from the haze family in beet fields and adjacent areas. The economic threshold of harmfulness at the beginning of beet seedlings is 0.5-1.2 beetles / m2; In the phase of 2-6 leaves, 10 larvae per plant. If this threshold is exceeded, insecticide treatment is required.