These beetles jump like fleas, but are not related to them. Both adult and immature flea beetles feed on a wide variety of garden vegetables. The immature beetle, a legless gray grub, injures plants by feeding on the roots and the lower surface of leaves. Adults chew holes in leaves. Flea beetles are most damaging to seedlings and young plants. Leaves of seedlings riddled with holes dry out quickly and die. Adult beetles spend the winter in soil and garden debris. They emerge in early spring to feed on weeds until vegetables sprout or plants are set in the garden. Grubs hatch from eggs laid in the soil and feed for 2 to 3 weeks. After pupating in the soil, they emerge as adults to repeat the cycle. There are 1 to 4 generations a year. Adults may feed up to 2 months.
Control flea beetles with an insecticide containing pyrethrins, carbaryl, or diazinon or an insecticidal soap when the leaves first show damage. Watch new growth for evidence of further damage, and repeat the treatment at weekly intervals as needed. Clean all debris from the garden after harvest to eliminate overwintering spots for adult beetles.
Plant Care for Cabbage Family