Garden Q&A: Are brown marmorated stink bugs here to stay?

For The Baltimore Sun

We were inundated with disgusting stinkbugs about five years ago. Then they seemed to disappear. I saw three on the window screen recently. Are they coming back?

The brown marmorated stink bug (or BMSB) never left and never will. It has already spread to 44 states, but we’ve had a bit of good fortune regarding these Asian invasive pests. After the first onslaught years, populations plummeted. Many factors can lower insect numbers, such as unfavorable weather and a surge of natural enemies. We do have native stink bugs, so some predators were already here, but not enough to explain the precipitous drop. Biologists have been studying Asian parasitic wasps of the BMSB in order to release them, but were still researching extensively to be sure they didn’t kill any of our beneficial insects. Then, suddenly, the parasitic wasps showed up in our environment, already laying eggs on the BMSB eggs (which the wasp larvae eat.) Seems they accidentally were introduced (multiple times but not from the research labs) and are flourishing, feasting on the BMSB. In the future, you should never see as many BMSB as you saw before. Be reassured the parasitic wasps are teensy, smaller than Roosevelt’s nose on a dime. You won’t see them either.

Do deer eat liriope and does it affect the plants’ health?

There is disagreement about where liriope falls on the deer menu. It’s listed as “occasionally damaged” to “seldom severely damaged.” If they are hungry enough deer will eat anything, but it is not their first choice. Deer appetites are fickle, and population rise can change eating habits, too. Liriope may grow beautifully for years unscathed in one part of the yard (even be invasive) and get hammered in another. Repeated foraging will weaken plants until they are unsatisfactory groundcovers.

University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Maryland’s Gardening Experts” to send questions and photos.

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