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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.

Banneker’s boxelder bugs, Boisea trivittatus


Boxelder bliss at Banneker.


Last week I had the pleasure of training Master Naturalists at Benjamin Banneker Historical Site in Catonsville, MD. This little gem of a park commemorates the self-taught African American who was an astronomer, surveyor of the federal District of Columbia, author of almanacs, and naturalist. A carful observer of plants and animals, his journal describes and predicts the occurrences of one of the Bug Guy’s favorite insects, Brood X cicadas, previously featured in several episodes of Bug of the Week. While guiding Master Naturalists at the Banneker Historic Site, we were amazed and delighted by swarms of amorous boxelder bugs intent on fulfilling their biological imperative of finding mates and reproducing.

Maple samaras will soon twirl to the ground and become food for developing boxelder bugs throughout the summer.


Like the brown marmorated stink bugs we visited last week, boxelder bugs have exited buildings and outdoor refuges where they survived the ravages of winter. Having depleted winter fat reserves, they now seek seeds and other sources of food to fatten up in preparation of finding mates, mating, and depositing eggs. Banneker seems to be exquisitely suited for boxelder bugs as the park is populated by many very large, old, silver maple trees, boxelder trees, and ash trees festooned with thousands of winged samaras, those little helicopter-like seeds that spin to the ground on a breeze. 




Ever wonder what the boxelder bug’s beak looked like?





Female boxelder bugs deposit eggs on many surfaces. Tiny nymphs will hatch and move to the ground to consume seeds and other plant tissues.


Once the mating game is completed, females produce hundreds of eggs which will be deposited on tree bark, fence rails, tool sheds, or directly on the ground. Later this spring eggs will hatch and tiny wingless nymphs will feed on plants during summer. Nymphs of boxelder bugs have black legs and short wing pads. Their exposed abdomen is red. As nymphs mature, their black wing pads grow longer and finally cover the abdomen as they molt to adulthood. Depending on geographic location, boxelder bugs complete one to three generations each year.






When mating, boxelder bugs remind one of Dr. Dolittle’s pushmi-pullyu with the female doing the pulling and the male scrambling along behind. Watch as she takes a break to lay a few eggs on the side of a shed.

Wing buds on the sides of boxelder bug nymphs elongate with each molt.


During late spring and early summer, the bugs move to boxelder, which is actually a member of the maple clan, and other seed-bearing trees. In autumn, swarms of bugs become a nuisance on sunny porches, siding, and around windows and doors as they seek overwintering shelter. They find their way into homes through cracks in the foundation, gaps in siding around windows and vents, and beneath doors if sweeps are in poor repair or missing. On cold winter days they are inactive, but when temperatures warm, as they have in recent weeks, restless boxelder bugs move about and make their presence known inside and out. Boxelder bugs are not harmful to humans or pets. They do not bite, sting, or reproduce indoors. However, if you squash them on your drapes or wall, they will stain.



Thousands of boxelder bugs enjoy a day in the sun on the side of a heavily infested home.


Coprophagy, the consumption of poop, is practiced by many insects including, apparently, boxelder bugs. This is likely a way to obtain minerals or other nutrients found in a bird dropping.


To limit the number of boxelder bugs taking up residence in your residence, eliminate overwintering places such as piles of lumber, rocks, and branches close to the house. Weatherproofing your home can also help bug-proof it. Caulk and seal vents and openings where electrical and plumbing utilities enter and exit the house. Repair or replace door sweeps and seal any openings around windows, doors, and foundation.  With the return of temperatures in the 70s and 80s, bugs know spring has arrived and it is time to get busy.  Beneath an ash or maple tree, take a moment to catch a glimpse of these curious bugs dressed in red and black.  



We thank Karen and Winnie for sharing Banneker’s boxelder bugs, the inspiration for this episode of Bug of the Week. The wonderful reference “Urban Insects and Arachnids: A Handbook of Urban Entomology” by William Robinson was used as a reference.