Fourlined Plant Bug

The fourlined plant bug is an occasional pest of flowers and other landscape plants in Iowa. The bugs are not picky eaters. They will feed on sap from over 250 different kinds of plants. Favorites are members of the mint family, but they feed on flowers, crops and weeds.

Plant bugs use piercing-sucking mouthparts to puncture the leaves and suck sap from the tissue. Immature plant bugs (nymphs) feed from late April to late June when they change into adults. The adults are present the remainder of the summer, though they only feed until approximately mid July. The adults lay eggs in the fall. These hatch the following spring and the cycle starts over. There is only one generation per summer.

The points at which these bugs puncture the plant leaves show the damage symptoms characteristic of this insect. Damage typically appears as a black or translucent spot, usually surrounded with a halo of different color.

Because fourlined plant bug is not a common pest in Iowa, we do not anticipate the damage and therefore do not apply protective sprays in May when spraying would be of significant benefit. Late sprays, that is, after the damage becomes apparent and after the nymphs are grown, are of no benefit. If only adults are observed or if damage is found and no insects are present, do not spray. Watering, pruning, fertilizing and other cultural practices that contribute to “TLC” should be done to promote plant health and recovery.


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