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December 1, 2008

Invasion of the boxelder bugs

Photo by me 

About once a day for the past two weeks, my wife and I have been finding bugs in our house. No, not hidden microphones. Real bugs. They're small - about the size and shape of a lightning bug. They're mostly black, with red trim. Very spiffy.

They're also easy to catch. They seem to have no interest in flying. And while they're pretty active, they are easily out-maneuvered, crushed and disposed of.

I managed to snap some pictures with my new digital camera (above). A little blurry, but you can see what they look like. Then I consulted University of Maryland entomologist Mike Raupp's Bug of the Week Web site. Clicked on the BOW Archive, scrolled down to late November and spotted a likely match from 2005: the boxelder bug.

Here below is Mike's commentary on this late-autumn home invader. We have no boxelder trees I know of. Maybe they're also partial to Bradford pear trees. We do have one of those that's dumped a huge mess of grape-sized pears on our sidewalk. Ick.   

Mike thinks that's plausible: "I found one reference of these guys sucking on fruits of plum, cherry, apple, peach, and grape in addition to the usual maple and ash seeds. So, I feel safe in speculating that fruits of Bradford pear are fair game.

"Since Bradford pear is considered by many to be an invasive pest, perhaps our little black and red friends are providing good service by thwarting the spread of this tree."


Anyway, like our recent unlamented house mouse, these critters apparently are simply looking for a warm spot to spend the winter. Have you seen any of them in your house?

Now Mike Raupp, from his Web site:

"What’s this, another home invader? This one is dressed in red and black. Is there an uprising in the air, perhaps, the entomological equivalent of the French Revolution? No, these are boxelder bugs.

"Boxelder, also known as ash-leaved maple, is a rather homely native tree and one of the favorite foods of boxelder bugs. Like their other “true bug” relatives, boxelder bugs have a beak with sucking mouthparts used to remove plant sap and the contents of seeds. In early spring, nymphs of boxelder bugs hatched from eggs laid by mothers that survived the winter. During the growing season, boxelder bugs ate the sap and seeds of boxelder and other species of maples as well as ash, plum, cherry, and many other trees, shrubs, and vines. Boxelder bug nymphs have black legs and short wing pads. Their exposed abdomen is red. As the nymphs mature, the black wings grow longer and finally cover the abdomen as they molt to adulthood. During late spring and early summer, they move to the boxelder trees, especially to female trees. I’ll bet you didn’t know that in some species, trees are male or female and in other species, trees are both male and female. How strange is that? Female trees bear winged seeds and male trees do not.

"The largest bug populations tend to build up on female trees where they feed on seeds. In autumn, usually October in central Maryland, the red nymphs and the black adults collect in masses on trunks of boxelders. In the wild, adults fly to rock formations, fallen leaves, or crevices in trees to gain protection from the wicked winter. In cities, suburbs, and the country, our homes provide just the right protection from the cold. Swarms of bugs become a nuisance on sunny porches and siding and around windows and doors. They find their way into our 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 hide, but when temperatures warm they become active.

"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, then they will stain. To limit the number of boxelder bugs taking up residence in your residence eliminate hiding places such as piles of lumber, rocks, and branches close to the house. As with other home invaders like brown marmorated stinkbug and crickets, you should weatherproof your home to help solve the problem. Caulk and seal vents and openings where electrical and plumbing utilities enter and exit the house. Repair or replace doorsweeps and seal any openings around windows, doors, and foundation. This will help save energy and help reduce headaches when this diminutive army of red and black storms your barricades."

Posted by Frank Roylance at 3:42 PM | | Comments (12)
Categories: Phenomena


Yep, we have them at our place (Glen Burnie). They were all over the outside of our townhouse in the summer, and started coming in in the fall. They're mostly gone now.

Up here in New Jersey we have the boxelder bugs as well as stink bugs.

I've disposed of 3 stinkbugs and about half a dozen of the boxelder bugs in the last two months.

There havve been a few in Timonium that have gotten inside.

I suppose the maple tree in front is a draw for them.

I had no idea that the tree could be male or female.

they are here in Sparks as well.

Yes, here in Ottawa Valley Canada, I just found about 10 of this little menace in our house. I am glad they are not harmful and they seem to hibernate behind my fridge area.

These "spiffy bugs" are EVERYWHERE in my office. They procreate constantly, and it makes interviews very uncomfortable. It is particularly disturbing when they have group sessions, and then one starts running dragging the others along. HELP ME eliminate these pests!!

We have these also here in Central PA. I have disposed of at least five today.

We have them in Mass. Also I have them in my house. I also have some brown stuff leaking out from siding. Was wondering if it was these critter's.

Up here near Niagara Falls, Ontario Canada, we get rid of approximately 20-30 a day from inside the house. Our cat has taken a liking to eating them, helping keep our house bug-free. Gross.

these bugs have a MASSIVE infestation in my house right now. ive killed a dozen in my room this evening and there has to be THOUSANDS in the house as im killing around 30-50 per day and its WINTER. im getting an exterminator before it gets warm and all hell breaks loose. also, they do indeed procreate indoors ive seen em in action.

We have them all over our kitchen and now in our living room. I kill dozens in a day. If you catch them in your hand, and I do, I get a tissue and squish it. If you hit them with your hand on the walls they will also leave a stain. I live in the south and it is starting to get warm. They were coming thru the vents in our apartment, up thru the sink, thru cracks in the walls, etc. So far they are only in the kitchen and living room in our bookcases. I have had an exterminator but this apt complex is old and they are in the walls and drains. I can't see where else they get in. They bring other small black bugs with them too. Raid has made a small fortune off of me. It's disgusting. They also multiply.....

Vastly relieved at the info this site provides - I see others from my area (Ottawa, Canada) also commenting. I thought we were alone with this infestation. Just yesterday I discovered a nest of the things under our front verandah, from where they were climbing up our brick walls and finding their way into the house. Our 3 cats seem to enjoy chasing & "eliminating" the ones which do get in someplace.

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About Frank Roylance
This site is the Maryland Weather archive. The current Maryland Weather blog can be found here.
Frank Roylance is a reporter for The Baltimore Sun. He came to Baltimore from New Bedford, Mass. in 1980 to join the old Evening Sun. He moved to the morning Sun when the papers merged in 1992, and has spent most of his time since covering science, including astronomy and the weather. One of The Baltimore Sun's first online Web logs, the Weather Blog debuted in October 2004. In June 2006 Frank also began writing comments on local weather and stargazing for The Baltimore Sun's print Weather Page. Frank also answers readers’ weather queries for the newspaper and the blog. Frank Roylance retired in October 2011. Maryland Weather is now being updated by members of The Baltimore Sun staff

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