by Laurel Robinson

In Eldersburg Tuesday night, there were nearly 100 people gathered in the public library by 6:45. By 7:00, there were another 50 people standing around the edges of the room and outside the doors. The speaker was almost late, due to the fact that all the library parking was full.

The topic?  The Brown Marmorated Stink Bug, which showed up in droves last year in many Eldersburg homes.  Stephen Allgeier of the University of Maryland Extension provided more than 90 minutes of well-researched answers to dozens of questions.  The Extension has set up an e-mail listserv that people can sign up for, and it will send out new information on the new stink bugs as it comes in from the USDA.

There are many varieties of stink bug, including the green ones that are native to Maryland and harmless.  The stink comes from glands in their sides, providing an excellent defense mechanism that deters many predators.  A small percentage of the human population do not detect the stink.

There is also an “aggregating” pheromone that they emit when they find a pleasant spot (such as the sunny side of your house), inviting other stink bugs to join them.  (This is NOT the same smell that gets emitted when they die, so don’t be afraid to kill them!) If you find a crowd of them outside your home, Allegier says that simply spraying them down with a hose will cause the stink bugs to relocate, and reduce the likelihood that they will crawl inside your home through a nearby crevice.

The Brown Marmorated Stink Bug originated in Asia. Researchers suspect they arrived in Philadelphia in 1996.  In 1998, the first one was spotted in Allentown, Pa.  In 2003, they were spotted in Hagerstown, Md., and in 2008 there was significant damage to orchards in West Virginia.  In 2010, there was serious crop damage in West Virginia, Maryland, New Jersey, Delaware, Virginia, and Pennsylvania.  On March 6, 2011, one was officially spotted as far away as Iowa.

These Asian immigrants feed primarily on fruits and vegetables – tomatoes, potatoes, fruit trees, berries, peppers, even corn and eggplant.  They do not have a chewing mouth, but with their straw-like tongue (proboscis), they stab and suck -- damaging the plant so that it bears less fruit, or damaging the fruit to the point that they cannot be sold.  Sometimes the puncture holes are not evident, but the fruit has rotten spots inside that are discovered once the fruit is cut.

A variety of pesticides have been tested; most have been found lacking.  Many of them send the stink bugs into a “moribund” state, where they appear dead, but they are alive again within a day or two.   The pesticides that are most effective are the ones that have been removed from the market due to their toxicity.

A parasitic wasp (a stink bug predator from Asia) is being researched, but will not be introduced into our ecosystem until the USDA is confident that it won’t cause other problems.  This could take years. The “quick fix” stink bug books that are on the market are full of inaccuracies and “snake oils, “ according to Allgeier.  He urges consumers to use caution with chemicals: use them only as directed, and be aware that if the label says the product kills “stink bugs,” it may refer to only native stink bugs, and not the Brown Marmorated Stink Bug.

For adult stink bugs found in your home, Allgeier recommends knocking them into a container of soapy water, and putting the lid on.  They will die in there after a while.

One other word of caution from Allgeier: check your small engines.  Adult stink bugs are currently wintering over in crevices everywhere, and they could be inside lawnmowers, snow blowers, and chainsaws.  The same goes for window air conditioning units.

Starting in May/June, the best strategy will be to destroy their eggs, which can be found on the underside of leaves. A female can lay 10 clutches of in a year, with about 25 eggs each.  From the eggs hatch mini stinkbugs, ready to eat and eventually reproduce.  If you can find the white clusters of eggs and crush them, you will potentially prevent thousands of new stink bugs over the course of the summer.

See the University of Maryland Extenstion page on stink bugs at http://carroll.umd.edu/homehort/PestManagement/Marmorated%20Stink%20Bugs.cfm


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