Brown Marmorated Stink Bug

The Brown Marmorated Stink Bug is a relatively new pest to the area. There are several different types of stink bugs native to North America, but this particular bug, originally found in Asia, was first discovered in Pennsylvania in 1996. It isn’t known for sure how the bug was introduced, but it was more than likely accidental, perhaps in a shipment of Asian produce. Since its arrival, the BMSB has become an invasive species due to a lack of natural predators; the flying insect has rapidly spread to at least 41 states, causing millions of dollars in damage to crops along the way. They are such a big problem that the United States Department of Agriculture has dedicated an entire team (and webpage) to learning about and decreasing the number of these pests.

Why are they called “stink” bugs?

Stink bugs get their name from their ability to release a foul smelling liquid from the underside of the thorax, right between the first and second set of legs. The smell, which is released when the bug is crushed, vacuumed, or otherwise disturbed, has been described as cilantro, citrus, dirty socks, skunk, burning rubber, or oil, depending on the nose. One thing everyone can agree on, though, is that the smell lingers long after the bug is gone.

What do brown marmorated stink bugs look like?

The brown marmorated stink bug is an insect and true bug. It has 6 jointed legs, a pair of antennae, three body parts, an exoskeleton, and in this case, a set of wings. Adult BMSBs grow to about ¾” long and are identified by their shield-shaped brown, grey, and/or green marmorated, or marbled, back. The antennae are banded with alternating light and dark stripes, and the legs can be either banded or mottled. The underside of this bug is a brown-grey color. There are several bugs that share similar features, such as the western conifer seed bug, the squash bug, and the various stink bugs native to North America.

Are brown marmorated stink bugs dangerous?

BMSBs are not dangerous to humans or animals because they do not bite or sting. They are, however, a danger to edible crops. Adults BMSBs will happily dine on peaches, apples, pears, berries, tomato, citrus, pepper, soybean, and corn crops, to name a few. Depending on the number of stink bugs infesting an area, the damage could be minor- bruising and “cat facing”- to the total destruction of an entire crop. In 2010, stink bugs caused $37 million in damage just to apple crops in the Mid-Atlantic. Once a desirable crop has been discovered, a stink bug will release an aggregation pheromone which attracts other stink bugs to the location. In other words, finding one stink bug on your tomatoes could mean that there are thousands right behind it.

Why are there so many stink bugs on my house?

In the spring and summer months, BMSBs are happy to make their homes in trees, gardens, and crops. Come September, the bugs start to look for a place to take shelter from the elements for the winter. Once a home has been found, the stink bug releases its aggregation pheremone, inviting thousands of bugs to join it. According to an ongoing survey performed by the USDA, stink bugs prefer brown, grey, and green homes made out of wood, stone, and cement. The bugs are less likely to be attracted to light colored homes or those made from aluminum. Homes in wooded and agricultural areas are more likely to see activity than those in urban areas. It wouldn’t be practical to re-side your house in aluminum, but there are some other precautions you can take to prevent BMSBs from entering your home. Make sure all cracks around the home, including foundation, windows, doors, and siding, are sealed.  Stink bugs are attracted to light, so keep outdoor lights off at night and keep window blinds or curtains closed. Try to reduce areas of moisture using a dehumidifier, or by fixing leaky pipes. Make sure to keep food in sealed containers, so stink bugs will not have any food to seek out. After all, they come into homes because the food is more abundant than it is outside under the snow. If stink bugs do make it into your home, try to avoid stepping on them as this will release their odor. Some people drop the bugs into a solution of dish detergent and water, some flush them down the toilet, while others prefer to vacuum them up. If you choose to vacuum, be sure to seal and discard the contents immediately, as vacuuming will cause the bugs to release their signature smell.

Why are BMSBs so out of control?

Because they are not native to this continent, BMSBs have no natural predators. Yet. The USDA has been working on breeding a natural predator, and they are on track to release it into the wild within, perhaps, a year. In Asia, a BMSBs natural predator is the Asian parasitic wasp. There are easily millions of species of parasitic wasps native to North America, with each preferring a different type of pest to prey on; however, none of these naturally parasitize brown marmorated stink bugs. To combat this problem, scientists are working to breed the Asian parasitic wasp with a native U.S. wasp that will work to dwindle the BMSB population. The female parasitic wasp lays her eggs in the egg of a bug, and within two days, a tiny wasp emerges from the shell instead of a stink bug. With the mention of the word wasp, some people may think they would prefer to deal with stink bugs, since the wasps most of us are familiar with are large and deliver painful stings. Parasitic wasps are tiny, about the size of a period in a newspaper, and there are already hundreds of thousands of them in any given garden. The introduction of another species would go unnoticed by the average person.