Not all stink bugs are bad and few do crop damage, but the brown marmorated stink bug has been found in Napa. And this one is a different story.
This stink bug was accidentally imported to the United States in the late 1990s. Since then it has hitchhiked and spread across the country, leaving a wake of vegetal destruction.
Unlike most stink bugs, this one has proven to be a devastating pest to agriculture crops, with research reporting that many backyard gardeners in the Mid-Atlantic states lost all their susceptible crops.
“All their susceptible crops” packs quite a wallop. The list of more than 160 known hosts includes peaches, nectarines, apricots, plums, soybeans, tomatoes, corn, apples, pears, legumes, grapes, pecans, cucumbers, pole and bush beans, peppers, raspberries — you see the problem. As distressing and long as the list is, expect new crops to be added as the stink bugs discover their taste for them.
The brown marmorated stink bug does damage by sucking moisture from fruits, vegetables, trees and shrubs. It does not like leafy greens, root crops, onions or grasses, but otherwise, it likes what we like. These gadabouts can take one nip out of each fruit they pass. Unfortunately, just a little damage makes most fruits or vegetables unmarketable or inedible.
Brown marmorated stink bug nymphs and adults pierce fruits and vegetables with sucking stylets, causing fruit to appear sunken, misshapen or discolored. The broken skin increases susceptibility to secondary pathogens. And attacks at the early fruiting stage can cause plants to abort their crop altogether.
Local problems can become regional problems quickly if these stink bugs are not controlled when found. They multiply quickly and can fly up to 70 miles a day.
Adults measure about five-eighths of an inch long. They are marbled brown and distinguished from other stink bugs by tiny yet distinct differences, such as white stripes on their antennae. A stink bug in your garden, a neighborhood child and a magnifying glass could become a teachable moment this summer and fall. If you find a bug you think may be a brown marmorated stink bug, put it in a jar and bring it down to the agricultural extension office at 1710 Soscol Ave., Napa.
All stink bugs are fast and can see you coming. They go through five different stages of development, and knowing how they look during each one can help you find and destroy them.
After sheltering through the winter, adult stink bugs mate and lay barrel-shaped eggs in clusters in the spring. These are reasonably easy to see if you are looking. Detecting and destroying eggs and small nymphs at this stage is probably the easiest and most effective control. Wipe or spray eggs off.
Helping you at this stage are predators you might consider pests, such as earwigs. They eat stink bug eggs and help break down other components of your soil, too. Other natural predators of stink bug eggs include Asian lady beetles, pirate bugs, jumping spiders and spined soldier bugs.
At the nymph stage, assassin bugs, praying mantis and lacewings join in. The “Stop BMSB” website is a terrific resource that shows all stages of the pest’s development, what damage on different crops looks like and everything else you need to know about brown marmorated stink bug.
Fall is when you are most likely to see stink bugs congregating on outside walls, coming out of cracks around windows or doors or emerging from loose bark on trees. If you see them on structures, check the University of California’s Integrated Pest Management Pest Notes (http://ipm.ucanr.edu/PMG/PESTNOTES/pn74169.html0) for information on how to control them.
Properties near woodlands are often susceptible because the stink bugs naturally disperse from forests and wildlands. The bugs are often attracted to lights. If they congregate on your porch, move the light or set a trap to catch and destroy.
To trap stink bugs, fill a dish tub or bucket with water and detergent. Place it in a dark place or room and shine a flashlight into it. Bugs will be attracted to the water, and you can pour them out in the morning.
Some insecticides effectively kill brown marmorated stink bugs, but unfortunately, they kill the beneficial bugs in your garden, too. For that reason, the University of California recommends managing them other ways.
Hand-picking them is effective, if you can catch them. But then you need to squash them. Ew.
Probably the best way to deal with stink bugs is to avoid being attractive to them in the first place. Eliminate places for them to overwinter on your grounds, clean summer beds, pick up debris and cut back weedy corners and overgrown shrubs.
Do you want to become a UC Master Gardener of Napa County volunteer?
To obtain an application you must attend an information meetings. For dates, location and times, or to learn more about the program and volunteer commitment, see the UC Master Gardener of Napa County website.