Summer Houseguests vs. Fall Squatters: Elm Seed, Boxelder Bugs

Posted by Mosquito Squad Plus

August 18, 2026

Summer Houseguests vs. Fall Squatters: Elm Seed, Boxelder Bugs

Elm seed bugs and boxelder bugs are similar in appearance, but both have very different ideas about the ideal time to visit.

One of them is looking for long-term accommodation, seemingly showing up ready to sign a lease.

The good news is that neither of these bugs is particularly dangerous. That said, the numbers in which they gather can be cause for alarm. Add to that their propensity for squeezing through tiny openings around our home can turn a would-be relaxing day into an unwanted bug-watching event.

If you don’t like bugs in general, you won’t like either of these guys!

Elm Seed Bugs: Unsought Summer Houseguests

Much of their outdoor existence is spent eating elm seeds – thus the name, elm seed bugs. These unwanted guests show up during the hottest periods of summer and immediately set out to find the coolest room in our house in which to escape the heat.

But when temperatures start to climb, these undesirable invaders start looking for relief beneath our home’s siding, around shady windows, and if at all possible, inside our home.

Often mistaken for boxelder bugs, elm seed bugs are a brownish color with reddish markings. They can assuredly become a nuisance, gathering in large numbers around our home. Like stink bugs, elm seed bugs produce an unpleasant odor when disturbed or crushed. But they don’t bite or sting people or pets. They don’t produce damage to plants or trees or our homes. They don’t reproduce indoors.

In short, elm seed bugs are just…well, annoying.

And while they are less familiar here in the Greater St. Louis area than boxelder bugs, their presence is known to be expanding throughout parts of the Midwest.

Enter, Boxelder Bugs: Unsolicited Fall Squatters

Boxelder bugs wait for late summer or fall before making their move into our personal spaces. After spending the warmer months around boxelder and maple trees, this time of year, they begin gathering on sunny exterior walls. South and west-facing exterior surfaces are super popular with boxelder bugs, because they retain warmth as temperatures start to dip.

From there, boxelder bugs will begin their search for more protected and cozy winter accommodations. This makes cracks around windows, gaps in siding, and openings by utility lines vulnerable entry points, by which they make their way into wall voids, crawl spaces, attics, or other sheltered areas.

Boxelder bugs are black with orange-red markings that make them highly visible and maybe a bit nefarious looking. Overall, these bugs are also harmless, but their sheer numbers can be alarming. And while they’re not destructive, they can leave a stain behind on light-colored surfaces around our homes.

Different Schedules, Similar Poor Manners

It doesn’t matter whether they arrive in July or October. These bugs of opposing seasons have several similar habits. Both converge on the scene in large numbers, enter through small openings, and might emit an odor when disturbed or squashed. Neither of these bugs want to eat your home or cause it damage. They simply want to check in for seasonal accommodation.

Sealing cracks, repairing window screens, and replacing weather stripping can all make your home less vulnerable to elm seed bug or boxelder bug invasions. And if you have them indoors, it’s generally better to vacuum them up than to crush them. Take our word for it.

Mosquito Squad Plus can keep your yard and home ready for any season with Greater St. Louis pest control plans that put you one step ahead of bugs. Whether you require seasonal pest control with Barrier Treatment Plus, or year-round care with Squad Home Shield or Complete Home & Yard, our local outdoor pest control professionals are here to help you get bugs under control.

Where Do We Offer Bug Control in Greater St. Louis?

Mosquito Squad Plus is pleased to offer outdoor pest control services throughout the Greater St. Louis areas, including these towns and more.

Choose Mosquito Squad Plus for outdoor bug control in Greater St. Louis!

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