TLDR: Boxelder bugs eat seeds. Their main food is the seed pods of female boxelder trees, and they also feed on maple and ash. Now and then they poke at apples, plums, peaches, cherries and grapes. They eat nothing in your house. Very little eats them, because they smell and taste bad.
Boxelder bugs eat the seeds of boxelder trees. That is the short answer, and it explains most of what you see them do. I’m George Schulz, third generation at Better Termite & Pest Control, and the diet question comes up every fall when these bugs pile onto sunny walls around Northern Virginia and Maryland. People want to know what the bugs are after. It isn’t your house, your pantry or your siding.
Here is the full menu, with the university sources behind each line.
| Food | How often | What they take |
|---|---|---|
| Female boxelder tree | Main food | Seed pods, plus leaves and flowers |
| Maple, mostly silver maple | Common backup | Seeds |
| Ash | Sometimes | Seeds and leaves |
| Apple, plum, peach, cherry, grape | Occasional, late summer | Juice from the fruit |
| Strawberry and grasses | Rare | Plant fluid |
| Houseplants | Rare, no damage | A test poke at a leaf |
| Wood, fabric, pantry food, people | Never | Nothing |
What Do Boxelder Bugs Eat Most? Boxelder Seeds
The boxelder is a native maple, Acer negundo. Each tree is either male or female, and only the female trees make seeds. The seeds hang in long clusters of winged pods that look like the “helicopters” from other maples.
Those pods are what the bugs want. Colorado State University Extension calls boxelder seed pods their favorite food and notes the pods are found only on the female tree. The University of California adds that large numbers of the bug usually occur only on female box elder trees. They will feed on a male tree, but they don’t build up on one.
That is why one yard can be covered in bugs while the next yard has none. A single seed-bearing tree feeds the whole crowd. Around here boxelders like wet ground, so I look for them along creeks, drainage easements and the back edge of a lot.
Utah State University Extension reports that boxelder bugs “can feed and develop on many different kinds of plants, including maple, ash, stonefruits (cherry, plum, peach), apple, grape, strawberry and grass.” It then adds the part that matters: large numbers are typically found on female boxelder trees, where nymphs and adults feed on developing seeds.
What Trees Do Boxelder Bugs Like Besides Boxelder?
Maple comes second. Some people call these insects maple bugs for that reason. Silver maple is the usual backup, and the University of Massachusetts lists it next to boxelder as an occasional host. Silver maples drop their seeds in late spring, about when the young bugs start feeding.
Ash is third. Penn State Extension says the bugs are sometimes associated with ash and maple in heavily infested areas. In other words, ash is where the overflow goes when the boxelder tree is crowded.
They ignore oaks, pines and most other yard trees. If you find a cluster on an oak trunk in October, the bugs are sunning themselves. They are not feeding on it.
Do Boxelder Bugs Eat Fruit and Garden Plants?
Sometimes, and it is rarely a real problem. The University of California, writing about the western boxelder bug, says they may feed on almond, apple, cherry, peach, pear and plum fruit, and on grapes. The punctures can leave the fruit dimpled or misshapen. For the bugs we get in the East, the National Pesticide Information Center describes the same thing as minor deformities in fruit and leaves. Utah State puts the timing in late summer.
A backyard apple tree next to a female boxelder might show a few marked apples. A vegetable garden almost never shows anything. Utah State notes the bugs are not usually found on ornamental plants at all.
So do boxelder bugs eat plants? Yes, but only a short list of them, and they take fluid instead of chewing. You won’t see holes in leaves or missing stems. If something is chewing your hostas, look for a different culprit.
How Boxelder Bugs Eat
Boxelder bugs are true bugs, in the same broad group as stink bugs. They have no jaws. Their mouth is a thin beak, like a straw with a sharp tip. They push it into a seed, leaf or fruit and drink the fluid inside.
That one fact answers a lot of worried questions. A straw can’t chew wood, fabric, drywall or wiring. It can’t get into a cereal box. Penn State describes both the young and the adults as feeding by inserting their piercing-sucking mouthparts into plant tissue, and that is all the beak is built to do.
What do baby boxelder bugs eat?
The same things, starting with whatever is closest to the ground. The University of Massachusetts says the red nymphs hatch and feed on fallen boxelder seeds. The University of Minnesota measures a new nymph at about 1/16 of an inch, so last year’s seeds on the ground are an easy first meal. As the new pods form on the tree, the nymphs climb up to them.
What Boxelder Bugs Eat in Each Season
Their diet follows the seed crop. Our boxelder bug life cycle guide covers the timing in detail. This is the feeding side of it.
- Spring. Adults leave their winter shelter hungry. The University of Minnesota says they feed on plants and seeds on the ground during spring and early summer. Then they fly to female boxelder trees to lay eggs.
- Summer. This is the heavy feeding season. Eggs hatch in 10 to 14 days, according to Utah State, and the nymphs feed on seeds, leaves and twigs as they grow. In warm places a second generation follows the first.
- Fall. Feeding winds down. University of Maryland Extension says the bugs gather on tree trunks and then on buildings, usually in October in central Maryland. At that point they want warmth, not food.
- Winter. They stop.
What do boxelder bugs eat in the winter?
Nothing that matters. The adults that reach your wall voids or attic are waiting for spring. The National Pesticide Information Center says they remain mostly inactive until temperatures rise.
On a warm winter day a few will wake up and wander toward a sunny window. Colorado State notes they may try to feed on a houseplant but do no damage. They don’t breed indoors, and they don’t eat stored food, wood, clothing or carpet. A boxelder bug loose in the house is lost. It is not hunting for a meal.
No crumb or spill draws them in. They came in for shelter. If you want to know whether they cause any trouble while they wait, see are boxelder bugs harmful.
What Eats Boxelder Bugs?
Not much. This is the honest answer, and it is one reason their numbers get so big.
Boxelder bugs give off a bad smell when they are bothered, and the smell comes with a bad taste. Their red and black colors are thought to work as a warning label. Most animals that try one don’t try a second. If you have read why stink bugs are called stink bugs, it is the same defense in a milder form.
Utah State University Extension states that “boxelder bugs have few natural enemies.” No major insects or diseases affect their populations, and spiders are considered a minor predator. Birds fail to feed on them in any significant numbers, probably because of the offensive odor the bugs emit.
Here is what the university sources report for each kind of animal:
- Spiders. These are the only predator the sources agree on. The University of Massachusetts fact sheet says only spiders were observed feeding on them. A web near a sunny wall will hold a few. Spiders won’t dent a swarm of thousands.
- Birds. The same fact sheet says robins, blackbirds, thrashers and sparrows were not seen eating them.
- Lizards. Green anoles in Alabama were reported as possible predators. When they met the bugs, they avoided them.
- Cats. House cats have been seen spitting them out.
- Chickens, mantises, mice. You will see these named online. I could not find a university source that confirms any of them as a real control, so I won’t promise they will help.
So if you were hoping to bring in an animal that eats boxelder bugs, there isn’t one that works. Weather seems to matter more than predators. The University of Minnesota says they are most abundant during hot, dry summers followed by warm springs.
Dead ones are a different story. Penn State warns that carpet beetles may feed on dead boxelder bugs left inside walls. That is a good reason to vacuum up the ones you find.
Do Boxelder Bugs Eat Aphids or Other Bugs?
No. People ask this hoping the swarm on the fence is at least eating garden pests. It isn’t. Every extension source I checked describes them as plant feeders that live on seeds, leaves and fruit. None lists aphids, mosquitoes or any other insect as food.
The mix-up usually comes from look-alikes. Lady beetles do eat aphids, and they also gather on sunny walls in the fall. If you aren’t sure which one you have, our guide to bugs that look like ladybugs sorts them out. Colorado State also points to the small milkweed bug as a common look-alike. It feeds on milkweed seed, not boxelder.
Does Their Feeding Hurt the Tree?
Hardly ever. University of Maryland Extension says the trees “are not damaged by the feeding activity of the bugs”. The University of Minnesota reports no noticeable feeding injury on maple or ash either.
On a heavily loaded boxelder you may see some yellowed or curled new leaves. Penn State notes that fluid feeding can distort young foliage. The tree grows out of it. The seeds take the real hit, and the tree makes far more seeds than it needs.
Should You Cut Down the Boxelder Tree?
This is the one place where diet and control meet, so I’ll cover it and leave the rest to our other guides.
Removing a female boxelder does take away the main food. It often doesn’t take away the bugs. Both the University of Minnesota and the National Pesticide Information Center say adults can fly as far as two miles. Your neighbor’s tree, or one along the creek behind the subdivision, can feed the bugs that end up on your wall. Utah State’s view is that the value of the tree usually far outweighs the benefit of removing it.
What I’d do instead:
- Find the food. Look for a female boxelder or silver maple within sight of the wall where they gather.
- Rake up the seed pods under it in spring. That is the first food the new nymphs find.
- Pick a male boxelder or a different species if you are planting a new tree.
- Deal with the bugs on the house as a separate job.
For that last step, see how to kill boxelder bugs. It covers soapy water, vacuuming and when an outside treatment makes sense.
