Four-Lined Plant Bug

Four-Lined Plant Bug nymph

Four-Lined Plant Bug nymph

For the past two years I’ve had problems with Four-Lined Plant Bugs. As shown in the photo at left (click to enlarge), the nymphs are black and red, so they’re easy to spot, even though they’re only one-quarter inch in length. They have voracious appetites, and with their chewing-sucking mouthparts they can leave numerous small holes on tender leaves. The plant tissue surrounding the holes dies from the toxins injected by the bugs and appears as a series of brown, shot-hole marks or the holes can blend together into more of a blotch.

Four-Lined Plant Bug damage on Alchemilla mollis

Four-Lined Plant Bug damage on Alchemilla mollis

Four-Lined Plant Bug adult

Four-Lined Plant Bug adult

The nymphs emerge in early June, and, since damage occurs at the beginning of the growing season, they should be considered a serious pest since they reduce the amount of leaf surface for photosynthesis. Less photosynthesis means the plant  makes less of  its own food. As you can see from photos of typical leaf damage (click photos to enlarge), the nymphs and adults attack a wide range of plants. Although their favorite plants are Nepeta (Catmint) and Perovskia (Russian Sage), so far they’ve also attacked my lilies, Ligularia, Alchemilla mollis, asters, Veronica–and even the weeds! As for control strategies, my favorite approach to venting my rage at the plant bugs is to squish them in place. If you’re squeamish, try a spray of 2%-3% horticultural oil solution in water, neem oil, or pyrethrins.

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