Beetroot shield beetle (Cassida nebulosa L.) is a beetle 6–7 mm long, brownish-brown in color, with black specks of irregular shape. The elytra and pronotum are shield-shaped flattened and completely cover the body and head from above. The bottom of the body is black, flat. The larva is greenish, covered with serrated spines and setae, which are especially long at the end of the body. The pupa is flat, covered with spines.
Beetles hibernate in the field under the remains of plants or on the fringe of the forest under fallen leaves, and in early spring come out of wintering and first feed on weeds – quinoa and gauze, and when seedlings emerge, the beets switch to crops. Female shield nests lay eggs on the leaves of weeds, placing them in small heaps, while the female heaps of eggs are poured on top of the excreted liquid, which solidifies, forming a protective film. One female lays an average of 200 eggs; a maximum of one female can lay up to 1,000 eggs. Under natural conditions, the development of insects in the egg stage usually lasts 10-12 days, and at a temperature of 30 ° – 4 days, at 22 ° – 6-7 days. Eggs that develop from eggs feed on quinoa leaves; with strong reproduction, they can significantly damage beets. The larva lives 12-14 days, and then on the leaves, it turns into a chrysalis.
- to prevent mass propagation of shield beetles, weeds must be weeded out and removed from the field, otherwise, the shield-bearer larvae that developed from eggs laid on the weeds may pass to beets.
To destroy the shield beetles on beets, insecticides are sprayed.