We have had a number of questions in the Master Gardener Diagnostic Clinic about “stings,” discoloration and sunken areas that turn pithy under the skin, especially on tomatoes and peppers.

Adult stink bugs are a well-known family easily recognized by their shield-like shape, five-segmented antennae and for producing a most disagreeable odor when provoked. They come in various shades of green, brown and black. There are a number of species in this family that are known for unwanted feeding and vandalism of plant crops, including stone fruits, raspberries, apples, pears, tomatoes, peppers, corn, beans, squash, eggplant and cucumbers. They may also attack and damage ornamental plants.

You should pick and destroy stink bug egg masses or groups of young nymphs. Plants may be screened with floating row covers or similar barriers, but they must be placed over plants before stink bugs are present; however, for best fruit production this should be after pollination takes place. For more information see FS079E, Pest Watch: Brown Marmorated Stink Bug, available at https://pubs.wsu.edu.

According to WSU Extension, a statewide survey conducted in 1988 revealed 23 species of stink bugs in Washington. By 2014, this number had increased to 47 species, including the invasive and dreaded Brown Marmorated Stink Bug that was found in a handful of counties in Washington. Researchers have reason to believe more stink bugs exist in Washington state.

The Brown Marmorated Stink Bug is an introduced pest species from Asia that is spreading quickly across the United States. Nymphs and adults feed on a wide variety of plant hosts. BMSB prefers to feed on fruit, seeds and seed pods, but will also feed on stems and leaves of some hosts. Both adults and nymphs have piercing-sucking mouthparts and inject digestive enzymes into plant tissues to aid in feeding. On the surface of immature tomato fruit (green through pink stage), BMSB damage appears initially as a pinprick surrounded by a light discolored spot. Injured areas may turn yellow or decay as the fruit matures and fruits may become distorted or “cat-faced.”

Adults overwinter in sheltered locations (including houses, where they can become a significant nuisance). In the spring, light green to white eggs are laid on the underside of leaves. Young stinkbugs, or nymphs, are black with black and red striped abdomen. They often feed in groups of 20 to 30 on the underside of leaves. Adults are a little over a half-inch long with a shield-shaped body, which is mottled gray and brown with alternating dark and light bands on legs and antennae.

Note that Brown Marmorated Stink Bug adults closely resemble other stink bugs found in Washington and Oregon.

WSU Extension asks your help with additional information gathering on stink bugs. If you capture any bug that resembles a stink bug, we need the specimen (dead or alive) mailed to us along with information on the county, town or GPS location where the stink bug was found, the date found or captured and on what host plant the stink bug was found on.

Freeze them for 24 hours, place them in a plastic pill bottle and mail or bring suspected stink bugs to your local Master Gardener Program or to Mike Bush, Extension Entomologist, 2403 S. 18th St., Suite 100, Union Gap, WA 98903. You may also send digital images to bushm@wsu.edu.

• WSU Extension Master Gardener Program is an organization of trained volunteers dedicated to horticulture and community service. Questions about gardening, landscaping or this program can be directed to the Master Gardener Clinic at 509-574-1604 or you may leave samples for identification at the WSU Extension office, 2403 S. 18th St., Suite 100 in Union Gap. You can also email your questions to us at gardener@co.yakima.wa.us and include pictures if you have them. New volunteers welcome.