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Bug of the Week is written by "The Bug Guy," Michael J. Raupp, Professor of Entomology at the University of Maryland.

Stinky exodus underway: Brown Marmorated Stink Bug, Halyomorpha halys


This unpopular guest may soon be making an appearance in your home.


A delayed spring, following the winter that never ended, witnessed the arrival of honey bees and plasterer bees in recent episodes of Bug of the Week. With some truly delightful weather this week, stink bugs are on the move in homes and offices, accumulating on windowsills, walls, and doors, and buzzing about indoor lights at night. Why all the activity at this time of year?

Let us out of here!

The answer lies in the age-old pattern of life crafted by the stink bug to survive the ravages of winter and emerge just in time to take advantage of bountiful leaves and fruit found on plants each spring. Millions of folks throughout the nation were treated to invasions of stink bugs last autumn as the horde sought refuge in homes, schools, and office buildings. Many people mistakenly believe that stink bugs enter buildings in winter to “get warm”, but this is not the case. In the natural realm where stink bugs evolved over millions of years, stink bugs sought winter refuge in sheltered spots beneath the bark of trees, in rocky crags, and under fallen trees in the forest. Protected from the onslaught of winter, stink bugs chilled out and entered a season of inactivity akin to hibernation where they awaited the return of favorable temperatures and springtime food. Lengthening days and warming temperatures signaled the return of leaves, flowers, and fruit. With the return of food sources, stink bugs answered Mother Nature’s wake up call and moved from their refuges to the greening landscape.

Almost on a daily basis stink bugs march across my kitchen counter contemplating their escape to the greening world outdoors.

During the past week with warmer weather, we witnessed the arrival of early flowers and leaves on trees, shrubs, and herbaceous plants. Inside attics or beneath the siding on homes, these warm days have convinced stink bugs that spring has arrived and that it is time to return to the wild to seek food and pursue the biological imperative of finding mates and laying eggs. Having crossed the vernal equinox, and with our average daily temperatures now reaching historical daily highs, stink bugs have begun their springtime exodus from our homes into the natural realm. On warmish days this winter, in my home every now and then I collected a stink bug or two wandering about the kitchen or living room. But as of this week, these occasional sightings have turned into a steady stream and I collect stinkers daily.

In protected locations like attics, stink bugs likely survived winter’s chill.

As you deal with stink bugs this spring, here are some things to consider. Recently, I was asked if “stink bugs breed in my home?” To the best of our knowledge, the answer to this question is no. In the normal course of events, stink bugs move from winter refuges to plants outdoors where they feed for several weeks before they become competent to lay eggs. In your attic or an unused bedroom there is simply no food to provide the sustenance needed by stink bugs to produce eggs. Even if a stink bug laid eggs indoors on a windowsill or wall, there would be nothing to sustain the young bugs, which require plant food for growth and development. Having made this claim, I might back-peddle just a little, as we are receiving reports of stink bugs feeding on house plants such as orchids and potted ponytail palms. Will stink bugs lay eggs on houseplants indoors? One homeowner discovered a batch of stink bug eggs on a houseplant late in the spring. So the final answer to this jeopardy question is “yes”. However, the chances of a stink bugs sustaining a population in your home probably lies somewhere between zero and nil, unless you have bountiful fruit bearing plants in your home and do everything to ignore stink bugs dashing about on your plants.

Another question that always comes up is “what should I do about stink bugs that appear in my home this spring?” Sweeping, vacuuming, or simply picking them up and disposing of them is still our recommendation for control indoors. Because they will be active for a relatively long period of time, we are not recommending the application of insecticides to indoor living spaces to control stink bugs as they appear. Exposure of children and pets to pesticides could be worse than exposure of children and pets to stink bugs. In fact, many pets and some children will be amused by a few stink bugs wandering about.

Brown marmorated stink bugs aren’t shy about helping themselves to the bounty of your garden.

Will stink bugs be as problematic this year as last? As stink bugs continue to spread throughout the nation (they now occur in more than 40 states and two Canadian provinces) and as regions become generally infested, more people will witness stink bugs on their vegetables, fruit trees, and landscape plants outdoors, which will be followed by domestic invasions of stink bugs in autumn. But the news on stink bugs is not all bad. On a regional scale, most people agree that fewer plagued gardens during 2014 than in watershed years like 2010. Climatic events such as the polar vortex followed by the lingering cool wet spring of 2014, and elevated levels of predation and parasitism have been offered as potential explanations for this decline. Our brutal winter and chilly wet spring this year may help put the kibosh on populations of brown marmorated stink bugs in the mid-Atlantic region, and perhaps our farmers and gardeners will get another reprieve from this noxious pest. We will visit brown marmorated stink bugs again a bit later this year to learn what Mother Nature has decided for these rascals in the growing season of 2015. 


To learn what to do when stink bugs get inside and how to keep them out, watch the following video:


To learn more about the brown marmorated stink bug, please visit the following web site: