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 surfaces of leaves. Adults chew holes in leaves. Adult beetles survive the winter in soil and garden debris. They emerge in early spring to feed on weeds until vegetable seeds sprout. 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 for up to 2 months.
Control flea beetles on radishes with an insecticide containing pyrethrins or diazinon when the plants first emerge through the soil or at the first sign of damage. Watch new growth for evidence of further damage, and repeat the treatment at weekly intervals as needed. Clean up and destroy plant debris after harvest to eliminate overwintering spots for adult beetles.
Plant Care for Radishes