The beetles may also carry bacterial wilt disease. Control cucumber beetles by applying a suggested insecticide. Squash bugs can be a problem on older cucumber plants. They can cause considerable damage to the foliage and may even strip the plant of leaves. These insects are easy to control when they are young in the nymph stage but nearly impossible when adults.
Flea beetles are small, black beetles about the size of a large pinhead.
They eat numerous small holes in the leaves and tend to be more of a problem on young plants. Watch for buildup of colonies of aphids on the underside of the leaves. Use a suggested insecticide if these colonies appear. Pickleworm is the larvae of a moth that lays eggs in the cucumber flower and damages the young developing flower and fruit. The most common leaf spots, anthracnose and septoria, quickly defoliate a plant.