Archive for July, 2017

Stink Bugs 101

Friday, July 28th, 2017


     It’s summer now.  But fall will be here soon, and with it the dreaded annual stink bug invasion.  

     Not very many years ago I had no idea what a brown marmorated stink bug was.  Now I am all too familiar with these hard-shelled, shield-shaped, repulsive little critters.

     I believe it was 2010 or 2011 when I first heard of stink bugs, of their voracious attacks on fruit and vegetable crops, of their intrusion into homes in our mid-Atlantic region.  And not long after that my husband and I began to experience for ourselves these bugs’ noisy buzzing, noxious odor, and the stains they left on curtains and lamp shades.  Gross.

     I decided recently to find out more about our unwanted, ugly little house guests.  Why do stink bugs show up every fall now, when they were unknown before?  How serious a problem are they, and will we have to put up with them forever?  

     I found that the brown marmorated stink bug is native to Asia.  It was first observed in the U.S. in eastern Pennsylvania in 1998.  The bug had apparently entered our country accidentally in packing material or machinery that had been shipped to the U.S. from Asia.

     While the U.S. is home to more than 250 stink bug species, these natives have never posed much of a problem because predators have evolved as well, and those predators keep native stink bugs’ numbers in check.  Likewise, the brown marmorated stink bug is not a problem in Asia, thanks to predatory wasps that have evolved there to eat stink bugs’ eggs.

     But the unwelcome Asian stowaway has no predators at all in the U.S.  So once introduced, the bug spread rapidly.  By 2009 the brown marmorated stink bug could be found throughout Pennsylvania, and had also reached Maryland, West Virginia, Virginia, North Carolina, Tennessee, Kentucky, Ohio, and Illinois.  By 2012, brown marmorated stink bugs could be found in 40 states.  And that year, there were 60% more of these invasive stink bugs in the U.S. than there had been in 2011, just one year earlier! 

     While my own experience with the stink bug is at the level of annoyance, the major impact of the stink bug’s  rapid spread and huge population growth is on agriculture.  Especially in the eastern U.S., stink bugs are going after a wide range of crops.  They start eating in the late spring, and proceed to feast on  peaches, apples, green beans, soybeans, cherries, raspberries, pears, and many more fruits and vegetables.  They are also very fond of ornamental trees and shrubs.

     The stink bug possesses mouth parts that enable it to pierce plant parts and suck out the juice.  The loss of plant fluid leads to deformed or destroyed seeds, destruction of fruiting structures, delayed plant maturation, and increased vulnerability to plant pathogens.  

     For good reason, stink bug control has become a U.S. Department of Agriculture (USDA) priority.  But the brown marmorated stink bug is a formidable foe.  Not only does the lack of predators allow the bugs to spread and multiply, but they are very mobile.  A new generation of stink bugs can fly in after a resident population has been killed, making permanent removal almost impossible.

     And, unfortunately, the United States is proving an ideal environment for the brown marmorated stink bug.  There is no part of the U.S. where this stink bug cannot produce at least one new generation a year.  And in  warmer states like California, Arizona, Florida, Louisiana, and Texas, these bugs can produce as many as six generations in a single year! With overall temperatures rising as a result of climate change, reproductive conditions are becoming increasingly favorable throughout the country.  And the stink bug can survive long periods of cold as well as heat.

     Efforts to combat the brown marmorated stink bug have included the use of pesticides, but they have proven ineffective.  Scientists have looked at importing the stink bug’s natural predators from Asia as a way to keep their numbers in check here.  But introducing these wasps might result in yet another infestation.  Scientists hope that birds and other animals will eventually begin preying on stink bugs.

     Sadly, there is currently no known way to stem the increase of the brown marmorated stink bug in the U.S.  

     But at least there are steps we individuals can take to keep these bugs out of our homes in the fall, when the weather cools and the bugs are looking for a warm place to overwinter.

     Since insecticides have proven ineffective against the bugs, and may be harmful to humans besides, scientists recommend prevention.  Before fall arrives, cracks in walls, holes in screens, and spaces around air conditioners and utility boxes should be sealed.

     Despite one’s best efforts, some stink bugs will make it into the house.  And during a warm, sunny patch of winter, those who got into the house in the fall may awaken and start buzzing around.  ’Catch and release’ works okay, although if the bug is squad  a smelly emission can result.       

     Like many people, I throw stink bugs into the toilet.  That approach is less than satisfactory, since stink bugs are good swimmers, and some can make it to the side of the toilet bowl, where they crawl up to the rim.  Some people recommend keeping a bucket of soapy water at the ready and throwing bugs in.  I have not yet tried that approach.

     Sometimes during stink bug season, when I am reading on the couch in the evening, I keep a bowl of water, covered by a plate, on the end table beside me.  When I hear a loud buzz or spot one of those ugly critters on the lamp shade next to me, I grab it (not too tightly), lift the plate, plunge the bug into the water, and put the plate back on top.  The plate protects me from having to look at the bugs in the water, and it also ensures they can’t escape.  The next morning, without looking too closely at my catch, I toss the water and the dead bugs outside.


  • The brown marmorated stink bug can be distinguished from other, noninvasive, stink bugs by dark and light bands on their antennae and by dark and light bands on the top outer edges of their abdomens. 
  • Between May and August, female stink bugs lay 20-30 eggs at a time under a leaf or on a plant stem.  
  • The bug’s stink glands are located on the bug’s underside, between the first and second pair of legs.
  • Adult stink bugs live from several months to a year.
  • While stink bugs are more annoying than harmful to humans, the odor can produce an allergic reaction in some individuals who are sensitive to the odors of cockroaches and ladybugs.  If a stink bug is smashed against exposed skin, dermatitis may result at the point of contact.–April Moore





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