What are plant bugs?
- 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.
Types of plant bugs
Four-lined plant bug
- A pest in the garden in April-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 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 (adult). Johnny N. Dell, Bugwood.org
Four-lined plant bug damage. Photo: Matthew Borden, University of Florida, Bugwood.org
Yucca plant bug
- 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.
Yucca plant bugs. Photo: Jim Baker, North Carolina State University, Bugwood.org
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 below) turn brown and fall off.
- Adults appear around May and are gone by the end of June.
Honeylocust plant bug damage. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org
Honeylocust plant bugs. Photo: John A. Davidson, University of Maryland
Milkweed bugs
Tarnished plant bug on sunflower. Photo: Russ Ottens, University of Georgia, Bugwood.org