University of Maryland Extension

Plant Bugs

Yucca plant bug

Yucca plant bug

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Plant bugs are small sucking insects (2-9mm) that feed on the leaves of many herbaceous plants. The plant bugs feed by piercing the leaves with their tube-shaped mouthparts, injecting an enzyme into the leaf tissue and sucking up the partially digested fluid. Damage to leaves may appear as stipples (tiny white spots), small round holes and distorted leaves.

The four-lined plant bug is a pest in the garden in May and June (one generation per year). The adults are 3/16 of an inch long and yellowish green with 4 black stripes down the back. The nymphs (immature bugs) are red with the yellow and black wing pads partially covering the body. This bug feeds on over 250 herbaceous plants. Damage from this plant bug begins as yellow stipples or spots, eventually becoming brown to black necrotic spots. In large infestations, these spots coalesce and cause leaves to turn brown. Four-lined plant bugs are quick and difficult to detect, and only a few can cause noticeable damage. Because they move so quickly, they are difficult to control with a contact insecticide such as insecticidal soap or horticultural oil. Many plants will outgrow the damage by mid-summer.

four lined plant bug

four lined plant bug damage

plant bug damage on mum

Four-lined plant bug

Four-lined plant bug damage

Plant bug damage on mum

Yucca plant bug (see photo top of page) is a pest of Yucca wherever it is grown. The leaves are stippled, have black fecal spots and eventually turn yellow. The adult bug is 1/8th inch long, stout, and blue-black with a reddish head and thorax. The nymphs (young plant bugs) are red and may be found in large numbers feeding on the leaves.

The honeylocust plant bug is pale green with wings held flat on the back. Immature bugs look just like the adults, only smaller and with short wing bugs. The immature plant bugs feed on emerging leaflets in spring causing them to become distorted with yellow blotches. Eventually, the distorted leaves (see above photo) turn brown and fall off. Adults appear around May and are gone by the end of June.

honey locust plant bug damage

honey locust plant bug

Honeylocust plant bug damage

Plant bug

milkweed bug

Milkweed bug on Asclepias (milkweed)

tarnished plant bug

Adult tarnished plant bug

Boxelder bug

Harlequin bug

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