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Watch for fourlined plant bugs

People are starting to report fourlined plant bug damage in their gardens. You can recognize this feeding by looking for small, dark, circular, sunken spots on leaves. Fourlined plant bugs particularly like many types of perennials and herbs, like mint and basil.
An immature fourlined plant bug and its
damage on snow on the mountain.
Photo:  Jeff Hahn, UMN Ext.

What's it look like?

Both the immature nymphs and adults feed and damage plants with their piercing-sucking mouthparts. Immature fourlined plant bugs are bright red and 1/16th inch long when they first hatch.

 As they get larger, they turn reddish orange with black and yellow-green stripes. As adults, they are yellow-green with four black stripes and are ¼ - 1/3 inch long.

Will it hurt my plant?

The good news is that fourlined plant bug damage typically just affect a plant’s appearance, it normally does not seriously injure them. However, the amount of damage a gardener is willing to accept is subjective and will vary with different people.

Fourlined plant bugs will feed from June to early to mid-July. The sooner you can detect their feeding, the better you can minimize their damage. If you discover their presence, you have several options.

You can ignore the insects, especially if the damage is minor. Remember that fourlined plant bug feeding is mostly cosmetic. If you do that, continue inspecting your garden to make sure that injury does not become more severe later.

How can I get rid of them?

Adult fourlined plant bugs.  
 Photo: Jeff Hahn, UMN Extension
There are a couple of low impact options. Insecticidal soap can be effective, although.less so against adults. Pyrethrins can also be effective. Both of these insecticides must hit the insect directly to kill the insects. Repeat applications are probably necessary.

There is also a variety of residual garden insecticides, such as cyfluthrin, permethrin, and malathion, that are effective. One application should be sufficient.

For more information, see Fourlined plant bugs in home gardens.

Author: Jeffrey Hahn, University of Minnesota Extension

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