True Bug Tuesday: Brown Marmorated Stink Bug

Ok, ok, I confess. I watch that awful Animal Planet show Infested! What is often more appalling than the crises faced by the people showcased in the program are the rampant errors and hyperbole provided by many of the “experts.” One recent episode, however, was probably not overly exaggerated. It featured a family whose rural Pennsylvania home was overrun with Brown Marmorated Stink Bugs, Hyalomorpha halys, that were seeking winter shelter.

I have written about this invasive species previously, in a feature on ”Common Indoor Insects of Autumn”, having never seen one in person. That changed last year when my wife and I visited Cape May, New Jersey. Many structures, from buildings to Port-O-Lets, were being investigated by the bugs as potential winter hang-outs. The insects were also common on foliage and vehicles.

Since my first article, things have gotten even worse. H. halys is now found in most states east of the Mississippi River, plus the Pacific Coast states, and now Utah. Furthermore, it has elevated its status to that of a bonafide agricultural pest. In fact, it is essentially number one on the U.S. Department of Agriculture’s “most wanted” list.

The Brown Marmorated Stink Bug is what is called a “generalist” feeder, meaning that there are a wide variety of plants on its menu. Most insects are “host-specific,” unable to eat plants outside of one genus or family. The Monarch butterfly is a good example of a host-specific insect. The caterpillars can only eat the foliage of milkweed and closely-related plants. Contrast this picky diet with that of H. halys. Over 300 species of plants are palatable to it in the nymph and adult stages.

This versatility in host plants translates to a potent economic impact. The bug accounted for $37 million in losses to apple-growers alone in 2010. Other crops adversely affected include raspberries and blackberries; and organic farmers reported losses of beans, peppers, and tomatoes. The cosmetic damage alone can render some produce unsalable.

Like all true bugs, stink bugs feed on plant sap and juices through beak-like piercing-sucking mouthparts. Their sipping and sucking can cave-in corn kernels, wither fruits, and leave unsightly stains behind.

Adult male Brown Marmorated Stink Bugs also emit an “aggregation pheromone,” a kind of aromatic chemical cocktail that attracts other males, females, and nymphs to food sources. So, as if a single bug isn’t bad enough, he recruits friends and family. Scientists may be getting closer to using that pheromone as a weapon against the bug, by drawing them into traps, for example.

Back to that episode of Infested!. It had a happy ending. Initially demoralized by the overwhelming number of bugs holding them prisoner indoors and eventually infiltrating their home, the family turned the problem into profit. The father devised a light trap to attract and kill the bugs, and is now selling his invention to others.

Sources: Gibson, Caitlin. 2013. “Stink bugs could mount a comeback this spring,” The Washington Post, January 5, 2013.
Murray, Todd, et. Al. 2012. Pest Watch: Brown Marmorated Stink Bug. Washington State University Extension Fact Sheet FS079E. 5 pp..

Wasp Wednesday: Wasp vs. Bug

Back when I wrote about the Brown Marmorated Stink Bug, Halyomorpha halys, it was an introduced species from Eurasia that was no more than an indoor nuisance pest in the U.S. in the fall and winter. It has since ballooned into a certifiable agricultural pest in apple and peach orchards, and also vineyards. So panic-stricken are government officials that congress is attempting to pass a $831,000 “farm bill” to find ways of combating the bug. Enter a native wasp, Bicyrtes quadrifasciatus, pictured below.

The wasp is a type of “sand wasp” that preys on true bugs in the order Hemiptera, suborder Heteroptera. Each female wasp digs a burrow in sand, and stocks the cell at the end of the tunnel with paralyzed true bugs that will serve as food for a single larval offspring. Turns out that the Brown Marmorated Stink Bug has become a favorite target of the wasp, which hunts the immature stages of the pest (see figure below).

Alex Surcică has noticed this trend, and wants to document the efficiency of the wasps in controlling the bug. To that end he recently posted this message on his Facebook page:

"Seeking collaborators interested in collecting data on the nest provisioning of the sand wasp, Bicyrtes quadrifasciatus. This solitary (read non-aggressive) wasp occurs throughout North America, east of the Rocky Mountains, and it nests only in sand, along water ways or in sand volleyball courts and kids sandboxes. For making observations, one needs a garden trowel, pen, and notebook. The results of this citizen-science project will be used to assess the role the sand wasp plays in controlling the Brown Marmorated Stink Bug, a multi-million dollar pest. If interested, reply and I will send you more info. Please take an extra moment and share this with your FB friends. Thank you!"

Alex also posted a series of images on his “Bees, Wasps, and Other Beneficials” Facebook page that details how he painstaking excavates Bicyrtes nests to census the number of each prey species taken by the wasp:

“When I'm collecting data on the nest provisioning of the sand wasp, I'm waiting to see a female with her paralyzed prey entering her nest. While she's inside (sometimes can take minutes), I use a twig to mark the nest. I always position the twig three inches to the left of the nest entrance, and at a slight angle that will indicate later on where tunnel was leading to. Once the nest is marked, I search for other nests. Female sand wasps tend to initiate many nests but do not always end up using them. Therefore, I always mark only the nests that had females with prey entering them.”

I heartily applaud Alex for attempting this endeavor; and I encourage my readers to become part of his effort. Bicyrtes quadrifasciatus is common over most of its range, and several females may nest in the same general vicinity. So, once you find one nest, you are likely to find others.

Meanwhile, the U.S. Department of Agriculture is considering importing a parasitic wasp from the geographical area overseas where the stink bug is native. Introductions of parasites as “biocontrols” have not always ended well. There is the risk that the “new” parasite from abroad will find our native, non-pest stink bugs as acceptable a host as the Brown Marmorated Stink Bug. Maybe the native bugs would be even more attractive to the parasite. That kind of scenario has happened before.

I thank Alex Surcică for allowing the use of his images in this post as well. Do check out his “Bees, Wasps, and Other Beneficials” Facebook page for more stunning photos.

Indoor Insects of Autumn (part 3 of 4)

This is the third installment of a four-part series addressing insects frequently seen indoors at this time of year when they seek shelter for hibernation during the colder months. This entry will introduce the “brown marmorated stink bug,” Halyomorpha halys. Special thanks to John R. Maxwell for sharing his images.

Unlike the western conifer seed bug and the boxelder bugs, the brown marmorated stink bug is not native to the North American continent. It was first detected in Allentown, Pennsylvania in September, 1998 but probably arrived at least two years earlier. The insect hails from Asia, being indigenous to China, Japan, Taiwan and Korea.

Thus far, H. halys has amounted to a mere “nuisance pest” that appears in numbers on the exterior of homes as it seeks shelter for the winter. The adult insects fly well, and sometimes manage to creep indoors, much to the consternation of property owners. The fact that they can deploy their scent glands when under duress makes them even more unappealing.

Outdoors, during the spring and summer months, nymphs and adults feed on a variety of plants, shrubs, trees, and fruits. They sip liquid sap and fruit juices through beak-like mouthparts collectively called a rostrum. Their feeding causes mostly cosmetic damage and they have not yet attained pest status for that reason. This is not the case in their native range where they are especially problematic for soybean growers.

Unfortunately, these are non-descript bugs that are easily confused with innocuous native stink bugs like those in the genus Brochymena. Older nymphs like this one do sport distinctive spikes and spines, and black and white-banded legs. It is the aggregation behavior of the adults in the fall that seems to be their most unique and identifying characteristic.

Since its first appearance in Pennsylvania, the brown marmorated stink bug has been discovered in the following states: Connecticut, Delaware, Idaho, Indiana, Illinois, Iowa, Maine, Maryland, Minnesota, Mississippi, Montana, New Jersey, New York, Nevada, Ohio, Oregon, South Dakota, Tennessee, Utah, Virginia, Washington, West Virginia, Wisconsin, Wyoming, and the District of Columbia. Specimens have also been intercepted by agriculture officials in California and Florida. Should you suspect you have found this species in a state not on this list, you are urged to report your finding (backed up with specimens whenever possible) to your state department of agriculture.

As with all of the insects being profiled in this series, care should be taken to exclude the bugs from entry into structures by repairing worn weatherstripping, mending holes in window screens, and sealing other possible points of entry with silicone caulking and other such materials.