Three-Lined Potato Beetle

Three-lined potato beetles are found on plants in the family Solanaceae, including potato, tomato and relatives. They are uncommon on potato, rare on tomato, but very common on tomatillo (Physalis ixocarpa). Adults are 7-8 mm long (1/4 inch) orange-yellow, with three lengthwise black stripes. The females lay orange-yellow eggs in groups, usually on the undersides of leaves, by veins.
The larvae hatch in late June or July, and look a bit like slugs with legs and
black heads. They tend to stay in groups as they feed, rather than feeding individually. They cover themselves with their own excrement, probably as a defense to being eaten. After the first generation has completed its development, a second generation appears in August. Both the larvae and the adults chew on foliage. On potato and tomato the injury is usually minor, but injury can be severe on tomatillo.