Wednesday, May 28, 2014

Brown Marmorated Stink Bug, Part 1.

Adult Brown Marmorated Stink Bug
David R. Lance, USDA APHIS PPQ,
Many people are either unaware or only vaguely aware that there is a problem with imported pests.  We’ve all heard of fire ants and africanized honeybees and most of us in Kitsap county are aware that Scotch Broom is an imported invasive weed.  Even here in Kitsap, invasive organisms are more common than many of us suspect.  “Invasive” organisms are, mostly, animals and plants that are not native to our area and have the potential to cause some sort of damage.  Scotch Broom, Himalayan Blackberry, and Yellow Flag are all examples of invasives that we may like (pretty flowers or tasty fruit) but cause ecological and/or economic damage.  

On the other hand, some natives can be annoying but are not considered “invasive” because they are native.  Examples include salmonberry and horsetail, two plants that, in the right situation, can take over your garden, seemingly overnight.  Yes, horsetail is, perhaps surprisingly, a native in our area.  There are at least three species in Kitsap county.

From time to time, I will post about various invasives to look out for.  Some are already here in our state and county.  Others may not be here yet, but we should be on the look out for them.  This post is about one that is here in our state, but so far (fingers crossed) is not in our county as far as I know.  I’m referring to the Brown Marmorated Stink Bug (BMSB).  This pest, also known as Halyomorpha halys, is a double-whammy pest, being both a nuisance pest in homes and a significant feeder on agricultural and garden plants.  Thus it is as much a pest to the suburban homeowner as it is to the rural farmer.

All invasives are native somewhere on the planet and the BMSB originates from China where it is a pest although it doesn't cause as much damage there as it does in the United States.  It has spread to neighboring Japan and Korea where it has become a crop pest there as well.

BMSB was first detected in the United States in September, 1998 in Allentown, Pennsylvania, although it probably arrived a few years earlier.  It then spread quickly, becoming a nuisance pest, overwintering in buildings and feeding on abundant food sources with few natural predators.  By 2010, BMSB was causing severe agricultural damage in mid-atlantic states on crops such as sweet corn, tomatoes, apples, and peaches with some growers reporting total losses.  Also in 2010 the first sightings of BMSB occurred in Washington State but so far the insect is restricted to Clark and Skamania Counties.  Kitsap county, so far as we know, is free of this pest. Click on the map below for an interactive BMSB distribution map. Then click on our state for updated information on BMSB in Washington State.

Distribution of BMSB as of April, 2014.T. Leskey, USDA ARS.

As I’ve mentioned already, there are two types of problems caused by this pest.  The first is a nuisance problem where the BMSB will crawl into buildings as winter comes.  They’re looking for a safe place to make it through the winter and they often do it in large groups.  There is of course the “ick” factor just from all these bugs entering your home, office, garage, or whatever their structure of choice is.  On top of that though, there is the other factor, the reason they’re called stink bugs...they can emit a foul odor if disturbed.  I've not had the misfortune to smell the BMSB odor but others I’ve talked with report that it is indeed quite foul.

BMSB feeding on peach.
Gary Bernon, USDA APHIS,
The second problem with the BMSB, and the more significant reason we should be on the lookout for it, is it’s appetite for a wide variety of ornamental and agricultural crops.  BMSB is a significant agricultural pest.  It feeds on a wide range of food and ornamental plants.  In our state, it is likely to be commercially significant on apples, grapes, corn, berries, and various vegetables.  In and around our homes it will feed on many ornamental species including maple, birch, Katsura, Empress Tree, elm, and rose to name a few .  A list of 170 known hosts for BMSB is published on the web and updated as new information is learned.  This list can be found at:  Many of these plants are grown commonly in Kitsap county.

BMSB head.  Note smaller red eye spots.
Susan Ellis,
BMSB underside.  Note light and dark bands on legs.
Susan Ellis,
Identification can be a little tricky.  The nymphal (juvenile) stages differ notably from the adult stage and there are look-alike species in our area.  Examine the photos in this post.  You will see that the adults are mottled brown and grey.  Two characters that distinguish adult BMSB from other similar species are the alternating light and dark bands on the legs and antennae and the presence of two red ocelli (eye spots).  The red eye spots should not be confused with the true eyes.  They are set between and behind the true eyes (see photo to the right).  

In addition to using the photos from this post for identification, other resources are available.  See the “additional resources” below.
BMSB nymphs and eggs.
David R. Lance, USDA APHIS PPQ,

Part 2 of this article can be found here.

Additional resources

Thanks to Tess Haddon for editing assistance.

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