The Lehigh Valley could take more pride in our famous stink bugs. The North American debut of brown marmorated stink bugs (Halyomorpha halys) was first documented in Allentown, back in 1998. Since then, their popularity has spread to at least 36 states. Without causing any significant human illness, injury or hunger, they have stimulated a vibrant industry aimed at thwarting them. Compare our plucky stink bugs to malarial mosquitoes, fire ants or migratory locusts and they are relatively benign.
Some will say that the brown marmorated stink bug is not native, so it does not belong here. Earthworms are not native to most of Pennsylvania, having been introduced from Europe and Asia. Honey bees are also a European import. Why has there been such a strong negative reaction to stink bugs?
True, the brown marmorated stink bug has become a significant pest for some agricultural crops, especially apples and peaches. I am not about to leap to their defense in the agricultural arena. A quick search of the internet reveals the economic impact they have left in their wake. However, does the typical homeowner harbor such animosity to the spotted cucumber beetle ?
I am not a huge fan of stink bugs in my home. On the other hand, it’s easy enough to pick them up (with a tissue, if you are squeamish) and throw them out the door. A low-tech brush and dustpan can also do the trick for larger populations. Stink bugs will release a pungent perfume as a defensive strategy when disturbed. This includes tumbling down a vacuum cleaner hose. If you are sensitive to the fragrance of stink bugs, vacuuming is not the best option.
Indoor insecticides are totally out of the question. Not just because they are toxic to us. They are useless. Removing a dead stink bug from the house is no less work and not much more fun than removing a live one. The application of insecticides to the outside of a house to prevent them from entering is a temporary fix. Fortunately, the insecticides that have been approved for outdoor stink bug control are short-lived and broken down by sunlight within a few weeks.
The most effective way to prevent huge numbers of stink bugs from entering your home is to make sure there is not a lot of vegetation, especially trees, in direct contact with the house. Beyond that, seal up cracks around windows, doors and other gaps. This might help with your heating bill as well! They only reason they come inside is to find a safe place to spend the winter. They will never breed indoors. Some indoor stink bug traps work to a certain extent, but they will not stop the insects from coming into the house in the first place. Personally, I would rather spend my money on aromatherapy candles and watch the stink bugs as they go about their playful antics.
One thing to admire about brown marmorated stink bugs is that in addition to their two large compound eyes, they have little tiny “eyes” called ocelli on the top of their head. They are ruby red as Dorothy’s slippers. Some have described them as garnets inserted into a bronze sculpture. These eyes do not form an image like our eyes do, but are primarily light sensing organs. Some insects use them almost like GPS units as a navigational aid. If you look at the front end of the undercarriage of a stink bug, you will see they have a long flexible straw that they use to suck out plant fluids. This is what makes it a true “bug.” Another thing that I find fascinating about the brown marmorated stink bug is how they have evolved to feed on at least 200 different plants. Most plant-juice sucking bugs are limited to just one or a handful of foods. What makes them so special? Nobody knows.
Exciting research is underway to find natural enemies of brown marmorated stink bugs. One of the reasons the brown marmorated stink bugs have enjoyed such success here in North America is that they do not have many natural predators. USDA researchers in Newark, DE have found some promising leads with tiny parasitic wasps, but are appropriately cautious about introducing them into the wild. Brown marmorated stink bugs are just one member of the large stink bug family (Pentatomidae). The vast majority of these insects crawl under the radar screen of human notice or commerce. A few members of the stink bug family are highly beneficial predators of other insects. Before releasing exotic stink bug predators into the wild, it is extremely important to fully investigate whether they will stick to their intended targets or attack beneficial bugs that are not supposed to be on their menu.
In the fullness of time, natural enemies will catch up with our brown marmorated stink bugs. I predict that they will become a long-term, but scarcer part of our natural world. In the meantime, I have found that thinking of them as “watchable wildlife” has helped me tolerate them. At least as long as it takes me to summon the energy to chuck them out the door.