Aphids may be green, black, brown, red, pink, or some other color depending on the sap color of the host plant. They are usually slow-moving insects with somewhat pear-shaped bodies ranging from 1 /16 to 1 /8 inch long. There may be various sizes of wingless aphids (nymphs and adults) in a dense colony on a stem, on the underside of the foliage, or on the flowers. Later in the season, some may have relatively large, transparent wings. The slender antennae are conspicuous, and near the rear end of the abdomen there are two tubes called cornicles.