How to Get Rid of Boxelder Bugs Indoors

Vacuum the cluster on the sunny wall. Do not crush them. Crushing stains fabric and leaves a smell. Empty the bag outside, or freeze the canister overnight and empty it. These insects are boxelder bugs. Gardeners also say box elder bug, or maple bug, once. Three red lines sit on the plate behind the head, and the wings fold into a red-edged X.

They feed on seeds of female boxelder, and they also visit maple and ash. The tree usually lives. The fall job is the south or west wall and the living room, not a spray calendar on the maple. An indoor fogger will not finish bugs still sitting in the wall.

Vacuum the cluster. Do not crush them.
Three red lines behind the head confirm it.
Seal cracks they can walk through. A living-room spray will not rewind an open south wall.

Vacuum the cluster. Do not crush them.

Vacuum adults and nymphs on the siding, the window, and the sill. Do not smash them on paint or curtains. Crushed bugs stain and smell. Empty the bag or bin outdoors, then seal it, because live insects crawl back out of a full canister.

Outdoors, a hard hose stream knocks the same cluster off the sunny wall or the trunk. Insecticidal soap, or a dish-soap mix, kills only the bugs the spray actually hits. Test a small patch of paint first. Soap does not keep the next flight from landing. Fail if you crush them on the curtains and call that the finish.

Does dish soap kill boxelder bugs?

A soap mix kills bugs it actually wets, outdoors on a cluster. It does not rewind an open crack. Do not use it as a living-room spray. Vacuum indoors instead.

Three red lines behind the head, not a milkweed bug

The adult is about half an inch long, black, and flattened. Three red or orange lines run on the plate behind the head, one down the middle and one on each side. The wings rest flat and the red margins make an X. Young nymphs are bright red and lack full wings. Eggs start yellow and turn red on bark, leaves, or stones near a seed-bearing boxelder. They are not laid inside fruit.

The western boxelder bug is the same cluster job. Look on the sunny wall and on female boxelder seed strings. An orange-red insect with a black band across the back, sitting on milkweed, is a different insect.

Where you see it	What it is	Try this
Sunny south or west wall; black with a red-edged X	Adult boxelder bug	Vacuum or hose; do not crush
Bright red, no full wings, on seeds or the same wall	Nymph	Same move; soap hits them if you can wet them
Orange-red with a black band, on milkweed	Milkweed bug	Leave it; different insect
Brown or green shield on the siding	Stink bug	See green stink bug — not this X
Brown, on squash or pumpkin leaves	Squash bug	See squash bug — not this wall cluster
Orange and black on cabbage or kale	Harlequin bug	See harlequin bug — not this maple seed feeder

Is this a milkweed bug or a boxelder bug?

Milkweed bugs are orange-red with a black band and they sit on milkweed. Boxelder bugs are black with three red lines behind the head. They cluster on sunny walls and on female boxelder seeds.

A brown shield on the siding is a different insect

A stink bug is wider and shield-shaped, mottled brown or green, without three red lines behind the head. Fall invaders share the sunny wall. Do not run a fruit-crop spray here. See green stink bug.

Squash bugs are brown and live on cucurbit leaves. See squash bugs. Harlequin bugs work brassicas. See harlequin bugs. A red-shouldered bug on goldenrain is a cousin with a different host. Milkweed bugs stay on milkweed. Confirm the three red lines, then vacuum this insect. Do not paste those other methods onto the maple.

Are boxelder bugs the same as stink bugs?

No. A stink bug is a wider shield, usually mottled brown or green. This insect is a narrow black oval with a red-edged X. See green stink bug for that insect.

They do not wreck the maple

Boxelder bugs suck seeds and some new foliage on female boxelder. Maple and ash can host a few. Leaves may yellow or pucker a little. The tree usually lives. A dying maple has another cause. Cutting one seed-bearing boxelder is not the first move, because winged adults fly blocks, sometimes a couple of miles, from a neighbor's tree.

Sweep fallen seeds off the patio and the foundation strip so spring nymphs have less food at your wall. A lone female boxelder that loads the same south wall every year is a later judgment, not a reason to drop a healthy shade tree this afternoon. Soft fruit such as peach or apple can take a small dimple in a dry summer. That is cosmetic. It is not a reason to fog the living room.

Do boxelder bugs kill trees?

No. They suck seeds and some new leaves on female boxelder. A little yellowing is common. A dying maple has another cause.

Should I cut down my boxelder tree?

Not as the first move. Adults fly in from other trees. Sweep seeds and seal the wall. Cut a female tree only if it feeds the same south wall every year and you already sealed.

Seal the sunny wall before they walk in

They gather on warm south and west exposures, then push into gaps around windows, doors, vents, utility lines, and siding. Seal openings about an eighth of an inch and larger. Repair screens. Add door sweeps. Use caulk, mesh, or foam that fits the gap. Building color does not matter. Sun and cracks do.

They do not breed indoors. Bugs on the windowsill in January walked in last fall, or they are waking in a wall void on a mild day. They live only a few days once they are in the heated room. Sealing now cuts next fall's walk-in. It does not rewind bugs already behind the plaster.

Do boxelder bugs reproduce indoors?

No. They need trees and seeds. Indoor bugs in winter walked in last fall. Seal cracks so the next flight stays outside.

An indoor spray will not finish bugs still in the wall

Do not fog the living room. Aerosol bombs drive insects deeper into voids. Killing a colony inside the wall can leave dead bodies that feed carpet beetles. Once they are in the room, vacuum. It is not practical to treat the wall cavity as the plan.

Outdoors, insecticide is a last step for a history of heavy fall clusters, applied to the foundation and the gathering spots in late summer, on a label that names exterior use. Soap or a hose is the first outdoor hit. Skip the brand aisle if the missing step is an open weep hole or a torn screen. Fail if the plan is one fogger in the living room while the south wall is still open.

Should I spray inside for boxelder bugs?

No. Vacuum the ones you can see. A fogger misses the wall void and can drive more insects into the room. Seal the sunny wall for next fall.

Confirm the bug, then vacuum or hose

Confirm the adult. Black, about half an inch, three red lines behind the head, wings folding into a red-edged X. Bright-red nymphs in the same cluster count.
If it is a brown or green shield, stop and see green stink bug. If it sits on squash leaves, see squash bugs.
Vacuum indoors. Do not crush. Empty the bag or bin outside and seal it.
Hose the outdoor cluster on the sunny wall or trunk. Soap is optional and only on bugs you can wet. Test paint.
Seal gaps on the south and west sides: screens, door sweeps, caulk, vents. They do not breed inside.
Leave the maple standing unless one female boxelder feeds the same wall every year and you already sealed. Skip the indoor spray.

FAQ

Do boxelder bugs bite people?

They are not a biting pest. Rare defensive punctures can itch like a small mosquito bite. They do not spread disease. Vacuum them. Do not crush them in your hand.

Are boxelder bugs poisonous to dogs or cats?

They are not poisonous. Pets usually spit them out because of the smell. The mess is stain and odor if you crush them, not a toxin from the maple.

When do boxelder bugs go away?

Outdoor clusters fade when nights stay cold. Indoor stragglers keep waking on mild winter days until the last of last fall's adults die. They do not start a new brood in the house.

At what temperature do boxelder bugs die?

There is no household thermostat setting that finishes them. Heat in the living room wakes them. Cold outside stops the cluster. Vacuum the ones that walk in.