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Last Update:  11/11/15
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The boxelder tree, Acer negundo, (A-ser ne-GOON-do) is actually a very beautiful tree.  It can be the centerpiece of your yard.  If it's a female, it can also attract, in very large numbers, the boxelder bug - so known because of their
close association with the tree.  (Here's the leaf.)
boxelder leaf
boxelder tree, in winter

boxelder bug
The boxelder bug, Boisea trivittatis, formerly Leptocorouos trivittatis, is a true bug, of the order Hemiptera, which means half-winged.  Most Hemiptera are "good bugs" that is, predators such as Aquatic Bugs, Damsel Bugs, Ambush Bugs, Assassin Bugs, etc.  The boxelder bugs are sort of in the middle. They do very little damage to the trees they attack, but at certain times of the year they can become a nuisance.  Boxelder bugs develop by gradual metamorphosis, from egg, to nymph, then to adult.

You don't necessarily need to have or see box elder trees to have these bugs around. The bugs are attracted to the entire elder family, which includes all varieties of maple, an omnipresent tree.  The boxelder itself, is a tree naturally endemic to mostly lowlands or flood plains.  Boxelders are really considered a "trash tree," have been banned from several areas, and many municipalities will not allow female trees to be sold or planted. Some people have reported that they have been required to remove female trees - at rheir own cost.

If you have a severe problem with boxelder bugs every year, and feel you just don't want to tolerate them, you may want to consider removal of the female box elder trees. Male trees do not attract (as many) of these bugs, and when boxelder trees are planted, the males should be selected. You can distinguish between male and female trees in the spring and fall: In the spring, both have blossoms, but blossoms of male trees are corymbs (upright, small, with a branching effect similar to that of an umbrella); the blossoms of female trees are racemes (long and slender, hanging down). In the fall, only the female trees produce seeds, the type called samara or keys, similar in appearance to the paired "helicopter" seeds of maple. The clusters of seeds on female trees remain attached in winter. Maples, of course, are in the same family and boxelder bugs will cluster on those too. While they do little damage to trees, they can definitely damage the fruits they attack.

Milkweed bugs look remarkably like boxelder bugs until you compare the two together.  The differences are then quite obvious.  Milkweed bugs are primarily found on or near milkweed and some other plants of the same family.  Milkweed bugs are not normally found indoors - unless you have a field full of milkweed next door.
Milkweed bug

Boxelder bugs overwinter as adults in protected places such as houses and other buildings, cracks or crevices in walls, doors, under windows and around foundations, particularly on south and west exposures. They can emerge even in the dead of winter, when it's cold outside and the sun shines and warms up those hiding places.

In the spring, when the boxelder buds start to open, small red eggs are laid on leaves and stones and in cracks and crevices in the bark of female boxelder trees. The eggs later hatch into the young nymphs that are wingless and bright red in color with some black markings. The young bugs will usually congregate on structures or low vegetation around boxelder or other host trees until seeds are formed on the tree, which they will then start to feed on. They'll also be found on sheds or fences, sunning themselves.

Most of the problem is because, here in the Northeast at least, we have had a succession of warm winters.  Anytime this happens, there is a good chance that boxelder bug populations will be at an all-time high.  If we continue to have warm winters, we will continue to have large numbers of these insects.  Of course, this actually applies to almost all animals, insects and wildlife.  Winter always offers us a respite, so pray for the cold weather!  Most effective (against them) is a warm spell of a couple of days and then a rather severe cold snap.

You might think that the boxelder bugs are trying to get inside.  They're not.  They are sunning themselves on the outside of your house, so when the sun goes down and it gets cooler, they crawl into *SOMEWHERE* and wait until morning.

Trouble is, if these cracks lead to the inside of the structure, the bugs easily become lost inside your walls, and then may pop up on the inside, so it's really not "on purpose." Most outside insects cannot survive for long inside your home, but boxelder bugs are quite happy on the inside, so you usually have to do something about it, especially if you have LOTS.

The answer is:  Not a whole lot.  To explain.....

There are, of course, dozens of chemicals that are registered for the boxelder bug.  In addition to that, there are dozens of exterminators that are ready, willing and able to come out to your house and do something.

Save your money.  Chemicals (sprayed inside your home) are NOT the answer.  A much better solution is always at hand.  Use your vacuum cleaner.  If you spray them yourself, you're going to get everything all greasy with insecticides, because you'll use too much - everyone does.  Don't squash them, you'll get red stains.  On top of that, they also have a foul odor when crushed.  The ol' vacuum cleaner is your best bet.

The bugs themselves are absolutely harmless - very laid-back little fellows, they'll let you handle them, they're not dirty or anything and they won't sting you or eat anything inside your house.  The more you have, however, the more you'll notice that the bugs will "spot."  A nice word for you-know-what.  It is also quite difficult to remove the spots after a few hours.
You Stink!

Whatever you do, don't spend your money on an exterminator.  Unless he has the equipment, license and expertise to spray the boxelder trees - and at the proper time, not willy-nilly, whenever he needs a little spare cash.  Forget spraying or treating the inside of the building, it just doesn't make any sense.

As for spraying or treating the outside, it's up to you.  Certainly, if you have, say, thousands of these critters, as many people do, some kind of chemical treatment may be in the offing.  Some exterminators have had various degrees of success in reducing populations congregating around your home.  We generally do not recommend chemical controls unless the problem is in epidemic proportions.


Unfortunately, we know of no easy-to-use natural predators of these insects. They emit a foul odor when attacked, and, I'm told, they don't taste very good. My son's piranha would never touch them, the fish made short work of all other bugs, but the boxelders floated around for days, until fished out. Even our company peacock, who dines on most anything, leaves these little fellows completely alone...

Of course, there actually ARE natural predators of boxelder bugs, most of which you probably don't care to have around you....  Mice, rats, chipmunks, most of the other rodents, ducks, chickens, geese and other birds too.

But when there's so many bugs around, the same food gets tiresome.  Could you eat a thousand pizzas, even if you love pizza?  Methinks not. "Natural predators" has a nice sound, but it doesn't always work that way.

Although box elder bugs do have "biting" mouthparts, and a few people have reported being "bitten," they have no poisons or toxins, there is no long-lasting effects from their "bite," and this isn't something you have to worry about.

They don't eat anything on the inside of your house, including house plants, and they won't really do any harm you, your family or your pets. They are not poisonous if eaten, do not reproduce inside your home, are not dirty, nor are they vectors or carriers of any disease. They can, however, be quite a nuisance - in a direct relationship to the numbers that you have.

Box elder bugs on wall
We even see boxelder bugs in our own office, almost every year, even though there are no boxelder trees close to us. We do have an east-facing wall that gets the winter sun until noon - a perfect wall for boxelder bugs to sun themselves. You can see them on our wall.

By the way, we have never sprayed or treated this office (inside or outside) for boxelder bugs.  If we don't need it, we could hardly recommend it to you.

We only see a few - inside or outside.  The amount you see in the picture above is about the most we have had on the outside.  And there have been some days where we have seen 3 or 4 on the inside.  On the west side of the building they are never seen.

Not bad when you consider that the lady with the boxelder tree pictured at the top of this page used to see, inside her home, sometimes, hundreds per day - and more.  On the outside, the bugs were even more numerous, and could appear anyplace, in or on the house at certain times of the year.  This tree, by the way, was removed several weeks after the photo was taken, in the winter of 1998.  I happened to ask her in the spring of 2009, she reported she still saw a few on occasion outside, but she knows of other trees in the immediate area.

Amazingly enough, I get asked this a lot. THEY EAT BOXELDER TREES.... Well, actually, they eat the seed pods mostly, but the pods are only around certain times of the year.

The last time I was asked this, it was a nine year old little girl that told me she had a "pet" boxelder bug and she wanted to know what to feed it. In this case, if you don't have seed pods, they survive quite nicely on just the moisture from a cotton ball, if you dip it in water. In nature, they will also eat strawberries and some other fruits.

Box Elder Bug Control

Have the TREE sprayed, at the correct time for your area, each year, religiously, by a reputable tree spraying company that specializes in tree spraying.  If it is a small tree, you can do it yourself with a hand sprayer, but remember, you have to spray ALL parts of the tree.  If it's much taller than ten feet, it's best to let the pros do it.

To pick the right tree spraying company, follow the exact same instructions for
choosing your exterminator.

In South Jersey, the best time of the year is right around the first two weeks of May, and the proper method is to SOAK the trunk to run-off, spray all parts of the foliage (top and bottom) and the ground around the tree out at least to include the drip zone. The treatment should be thorough.

The best equipment to use for the best coverage would be a mistblower.  A mistblower creates a powerful air blast and injects the insecticide into the airstream. Several types are manufactured, from backpack types, to large, truck-mounted systems such as the one pictured.  The tree foliage receives a more complete treatment this way.  If this tree is too close to neighbors, the use of a mistblower might not be possible.  There are other methods your tree sprayer can recommend. Mistblowers are best used by professionals.

You can use any insecticide that lists box elder bugs on the label.  You have several kinds to choose from.  Forget all the hype, use the cheapest.  Not necessarily the cheapest COST - sometimes it's best for you to figure out how much finished solution each insecticide creates, if any, and how much you actually need.  If it is sold as a finished solution, needing no dilution by the user, it will be very expensive to use.

In addition to the insecticides, it is important to use surfactants and stickers in all foliage spray solutions to insure complete control.  The use of these will help you use a smaller amount of insecticide that offers longer protection.  You get more for less.

You can also use ordinary soap or detergent for the bugs. Detergent is a bit cheaper, so you want to use a low-sudsing formula as the suds will just get in the way. About two tablespoons per gallon is plenty. Soap (or detergent) is a toxicant for insects and can do a fairly good job of killing. It does not have a residual, so that once it's dry, it is no longer effective. Soaps strip the waxy coating from insect's exoskeleton and will kill pretty quickly. Most of the time you can use it every day. Watch out using it on painted surfaces, some soaps and detergents will stain if they're not washed off immediately. Also remember that many plants may also be sensitive to soap or detergent applications, especially when you're making numerous applications of caustic compounds.

If you're using this in a garden-type sprayer be sure to rinse the sprayer out each time. Soap or detergent can be damaging to the rubber parts of the sprayer. After rinsing, leave the sprayer open and upright so it will dry out easily. If it is to be stored for a long period, (over the winter) you can lightly coat the plunger with oil - WD-40 works
just fine.  If you're using any kind of insecticide,
follow these directions.

Of course you can only do this if it is YOUR tree.  Problem is, even after you cut down the tree, the bugs still show up - sometimes for years after.  And if any of your neighbors also have a tree, you can still have the same problems even if you take all your trees down.  Usually the offending tree will have others of the same kind scattered around a neighborhood that will cause enough interaction to keep the bug and tree populations more consistent.

The bugs are, however, cyclical.  Which means that some years they will be bad and some years they will be worse.  Plain and simple.

And if that isn't enough, it doesn't even have to be a box elder tree.  They attack that whole family.  They also attack strawberry plants, plums, grapes and all types of maple trees, among others.  So eliminating the source is usually not an option that always works.

This really works to your advantage.  Your house has thousands of places for these little fellows to get in.  But concentrate on the sunny side, or wherever you see the most of them.  Use caulk, or whatever sealant is appropriate, to seal off these cracks and crevices.  If you can seal up enough of these cracks it will make a difference.  DON'T do this when you are having the problem.  Wait until the time when they are at the minimum.  Otherwise, you'll trap them all on the inside, and you'll probably see them for months, no matter what you do.

If you have a problem in your basement or crawl space and have access, you can put a 20-40 watt florescent light down there, leave it on 24/7.  It will tend to keep the bugs in the crawl rather than come upstairs.  If you can suspend the lamp over a tray of soapy water you will drown the ones that fall in.  You'll have to attend to this on a regular basis for this to work right.

Boxelder bugs are good flyers, so we even see them in a center city environment, on the 18th floor of a high-rise office building.  And even though they are good flyers, they will often walk the distance from your tree to your house and will get inside at the foundation level.  Make sure all your doors are weatherstripped and basement windows are sealed tightly.  

If you have an accumulation of leaves around your foundation, boxelder bugs will use that too, and will also hide in mulch.  Instead of mulch, especially on the sunny side, use rocks. Those large, round river rocks are best.  They offer the least amounts of hiding spaces, and will help with other bugs too.  Technically, mulch around the foundation of a building is a no-no, it allows insects of many kinds to live right next to your home.

You can also do a great deal, to reduce the problem, by yourself.  As a recent reader of this page commented, "One must be vigilant about cleaning up after the trees themselves."  Be careful to rake and sweep all remains of the tree in the fall and all the blown in stuff in the spring. He claims his bugs are still around but their numbers are "greatly reduced and not a problem anymore."  They are quite long-lived.  We had box elder bugs for five years (or more) after we cut down a maple tree in the back part of the office property.  We left the chips and debris in place and the bugs just love that. Make sure you clean up that debris for the most effective (and non-toxic) control.

You can, and it sometimes works, build a stand-off wall that stands between your tree and the actual wall you are trying to protect.  Stand-off walls can be made cheaply, installed easily, and can possibly catch the brunt of a continuing boxelder bug problem.

Stand-off walls are installed only a few inches away from your actual walls, and painted a darker color to collect more heat.  They catch the sun first, and supposedly the bugs too, so something like this can help.  They should be easily removable for protection
and maintenance.  A description of a stand-off wall is

We wish it would be easier.  Don't bother looking for a "magic bullet" because none exists yet.  At least not in chemical form.  (Not in my opinion, anyway.)  Follow everything outlined right on this page and you will be doing everything you can, and will be getting the best results.  This, all by yourself, with a minimum of chemicals, and, in the original vein of the Internet (at least here on UnExCo.com) the information is free.

Still have questions? If so, we have a public Message Board where you can browse questions and answers on all subjects, including box elder bugs.

There are several sites, here on the Internet, that SELL information "on how to get rid of box elder bugs."  Beware that these sites prey on your insect fears, promise a "solution," but all they do is just COMPILE information they have gleaned from OTHER sites, (including this one) - they offer no more than what I have detailed, right here on this page.  So if you fall for that scam, make sure that you get a money-back guarantee for when you discover that the information you have just purchased is available all over the Internet - for free.  And good luck getting your money back....

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