Is there anything more frustrating than an army of shield-shaped stink bugs sucking the strength out of your tomatoes or zucchini? One day your plants look healthy, and the next they are decimated by this aptly named garden pest. (One good squish and you’ll know what we mean.)
There haven’t been many deterrents aside from dousing them with chemicals or picking them off by hand, said Glynn Tillman, a U.S. Department of Agriculture scientist in the Agricultural Research Service.
Happily, Tillman and her ARS colleagues have found a promising parasitoid champion. The heroes are tiny wasps, such as the Trissolcus japonicus, a.k.a. samurai wasps, which lay their teensy eggs on stink bugs eggs. When the samurai larvae hatch, they eat up the stink bug larvae inside, crawl out of the eggs and then fly away to start the cycle anew. Some species even lay their eggs on the backs of stink bugs, Tillman said, so their larvae feed on the living bug until (shiver) the bug is living no more. These non-stinging wasps are smaller than gnats, so they’re hard to see, but they’re prolific and extremely effective at killing stink bugs, Tillman said. The trick is attracting them to your yard.
Turns out parasitoid wasps have a serious sweet tooth: “They have to have sugar to reproduce,” Tillman said. So farmers and gardeners can lure the wasps by planting nectar-producing flowers among their crops. If you plant the right flowers, the wasps will come, she said. Their favorites include wild milkweed, alyssum, buckwheat, sunflowers and two herbs, dill and cilantro, which should be allowed to flower.