Egg - The barrel-shaped egg, about 1 mm long, is light gray or pale yellow. It has two black bands -- one at the top, the other near the bottom -- and a black spot just above the lower band. Eggs are laid in clusters on crucifer foliage.
Nymph - The oval nymph is similar to the adult in coloration, but is slightly smaller and lacks wings.
Host Plants - Harlequin bugs attack nearly all crucifers, including common weeds of the mustard family such as wild mustard, shepherdspurse, peppergrass, bittercress, and watercress. If infestations are heavy and food becomes scarce, harlequin bugs will also feed on squash, corn, bean, asparagus, okra, and tomato.
Damage - Adults and nymphs pierce stalks, leaves, and veins with their needle-like mouthparts and extract plant juices. Stems and leaves injured in this manner develop irregular cloudy spots around the puncture wound. Young plants are likely to wilt, turn brown, and eventually die; while older plants are only stunted.
Life History - Harlequin bugs overwinter as adults throughout most of their range. They remain active throughout the mild winters of the Gulf States, but hibernate among plant debris during the harsh winters of northern states. Adults emerge early in spring. Approximately 2 weeks after resuming activity, females begin depositing eggs on the undersides of leaves. Eggs are laid in double-row clusters of 10 to 13 until each female has deposited approximately 155 eggs. In early spring, eggs hatch in about 20 days. Eggs hatch in 4 to 5 days as the weather becomes warmer. Nymphs feed for 6 to 8 weeks and develop through 5 instars before becoming adults. Two to 4 generations occur each year in North Carolina.
For chemical control of harlequin bug infestations, insecticides should be applied when bugs first appear and applications repeated as necessary. For recommended insecticides and rates, consult the current North Carolina Agricultural Chemicals Manual.
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