Both adults and larvae chew leaves of potatoes, tomatoes, eggplants, and related plants, including petunias. Feeding can kill small plants and reduce yields of mature plants.
Overwintering adults emerge from soil in spring to feed on young plants; after feeding, females lay up to 1,000 eggs during their lifespan of several months. Eggs hatch in 4 to 9 days; larvae feed 2 to 3 weeks, then pupate in soil. Adults emerge in 5 to 10 days. Two generations in most areas, three generations in southern states.
When overwintering adults begin to emerge, shake adults from plants onto a dropcloth in the early morning. Dump beetles into soapy water. Pick off adults and larvae. Scout for eggs on undersides of leaves and destroy. (Note that the orange-yellow eggs resemble lady beetle eggs.) Attract native predators and parasites with pollen and nectar flowers; mulch plants with a layer of straw at least 4 inches deep; cover plants with floating row cover until harvest, or at least until midseason; for large plantings, release two to five spined solider bugs per square yard of plants; apply parasitic nematodes to soil to attack larvae as they prepare to pupate; apply Beauveria bassiana or spinosad to kill larvae; as a last resort, spray infested plants with neem.
Photo: Clemson University, USDA Cooperative Extension Slide Series, Bugwood.org