The Bagrada bug, Bagrada hilaris, (also known as the painted bug or harlequin bug) is a serious pest of many vegetable crops in East and Southern Africa, Southern Asia and Southern Europe.

This bug attacks a broad range of vegetable crops such as cabbage, cauliflower, broccoli, kale, turnip, mustard and radish. This bug also damages papaya, potato, maize, sorghum, cotton, capers and some legumes.

The bug feeding causes large stippled or wilted areas on leaves. The growth of newly formed central shoots or heads often becomes stunted. This pest was not known to occur in California and other areas of the United States until it was found in June 2008 in Pasadena. Since then, it has been found in Orange, Ventura and Imperial counties of California and Yuma County of Arizona.

• Life cycle and description

The adult bug is about a quarter inch long and eighth of an inch broad at its widest area with a shield-shaped body. The upper surface is black with distinctive white and orange markings. The female adult is longer than the male. Adult females lay eggs in clusters on leaves or on the soil underneath host plants. Eggs are barrel shaped, initially white and then turn orange. Eggs hatch in five to eight days. A female bug can lay up to 100 eggs within two to three weeks.

The nymph is wingless and passes through five instars. The initial color is white and then changes to red with dark markings. The life cycle takes three to four weeks. The number of generations per year is dependent upon the climatic conditions.

• Damage

Adults and nymphs of the Bagrada bug insert their needle-like mouth parts into young leaves and suck out sap, resulting in large stippled or wilted areas on leaves, stunting and possible death of seedling plants. When young seedlings are attacked, feeding at the growth terminal can cause branching such that multiple heads are formed on crops like broccoli and cauliflower. Heavily attacked plants may have a scorched appearance.

The highest levels of damage have been seen in organically-grown fields, community gardens and residential gardens. Frequent cultivation will help to control eggs that are laid on the soil in vegetable fields. Sanitation of crop residue after harvest can reduce the carry-over between crops and seasons.

Thus far, effective biological control organisms have not been identified. Malathion, pyrethroid and neonicotinoid-based insecticides are effective in minimizing the damage. What to do if you see the Bagrada bug? The Bagrada bug has not been detected in the Central Coast area. If you suspect the presence of Bagrada bug, please contact Jian Long Bi, entomology farm advisor at our Cooperative Extension Office at (831)-759-7359.