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Basement Insect Identification: Common Insects Found in Your Basement (With Photos)

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Basement Bugs: When to Worry and When Not to

This guide describes the most common bugs and insects found in basements. For each species, it gives identifying characteristics and suggests ways to respond.

Only a few basement insects are reason for concern—most are in your basement to catch pest species like flies and mosquitoes, or to consume detritus and gunk that accumulates in your home's dark corners. These basement bugs are your home's free nighttime cleaning crew.

Basement Bugs: Identification and Recommendations

Basement BugIdentificationShould You Worry?

Termites

Look like small, pale ants

Yes. Termites are a serious problem.

Brown Recluse Spider

Large spider with "violin" mark on back

Yes. These spiders have a potentially dangerous bite.

Black Widow Spider

Large black spider with a red hourglass mark

Yes. Bites can be serious.

House Centipede

Fast, brown, many long legs

No. These bugs are beneficial.

Silverfish and Firebrats

Small, fast, silvery, fish-shaped

No. These bugs are beneficial.

German Cockroaches

Brown, leathery wings, fast

Yes. Cockroaches can be a major pest.

Phorid Flies (Drain Flies)

Tiny black flies

Not a serious problem, but can be annoying.

Millipedes

Tubular, slow, many legs

No. These bugs are beneficial.

Pill Bugs

Roll up into perfect spheres when disturbed

No. These bugs are beneficial.

Close-up of a termite

Close-up of a termite

Termites

Termites look like pale little ants, but they are not ants and do much more damage. A termite colony, established in the beams and wood siding of your house, can literally destroy your entire home.

The basement is one place in your home where you may notice termites. Keep an eye out for these early warning signs of a termite infestation:

Watch to Watch for

One of the earliest signs of an infestation is termite droppings. This is often the first thing that you'll notice when you have a termite problem. Termite poops tend to accumulate in piles underneath the spot where they have attacked wood in your house. This is an up-close view of termite fecal pellets:

Termite droppings are often the first thing homeowners notice

Termite droppings are often the first thing homeowners notice

Dead Insects and Wings

Another sign that you may have termites is high numbers of dead insects and discarded wings accumulated in certain areas. These can be found anywhere, but especially in casement windows in your basement, or just outside your house. When termites swarm and move into new areas, they fly, but once they settle in their wings drop off and they become more like ants. Many termites die in this process and can be found along with the wings around walls and windows.

Termite Tubes

Subterranean termites, which attack parts of your house that are in contact with the ground (like areas around your basement) make very visible tubes on surfaces where they travel. Termites construct these tubes so they can move around and still be protected—they are basically above-ground tunnels. Here is what these tubes look like on a wall:

Termite tubes are a sign of an infestation

Termite tubes are a sign of an infestation

Brown Recluse Spiders

Brown recluse spiders are sometimes called "wandering spiders." This is because they capture prey by wandering around until they come across another insect they can catch, kill, and devour. Males will also wander in search of mates. Most of this activity occurs at night, which is often when people get bitten. It's worth remembering that brown recluse spiders, and all other spiders, do not seek out humans to bite. When a spider bites, it's because it's in fear for its life, and is biting in self-defense.

Brown recluse spiders spin webs in basements, cellars, and garages. They use these webs as a place to hide, hence the common name of brown recluse.

Brown recluse, showing the characteristic violin mark on the back

Brown recluse, showing the characteristic violin mark on the back

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How to Identify a Brown Recluse in Your Basement

The best identification mark for a brown recluse is a mark on the spider's back that looks like a violin. This feature also gives the species another common name, "fiddle-back spider." If you find a medium-to-large brown spider with a clear violin-shaped mark on its back, try to get a picture and send it to a university, museum, or ag extension office. Do not try to capture the spider, but you can place a jar or glass over it to keep it in place.

Sticky traps catch many basement insects

Sticky traps catch many basement insects

Control of Brown Recluse Spiders in Your Basement

If you do have a brown recluse in your basement, don't panic! There are effective, affordable remedies. One of the best is a few sticky traps, which are good for brown recluses since they wander around and are more likely than other spiders to get stuck in one of the traps.

If you decide to call an exterminator, remember that this solution will also kill all of the beneficial insects in your basement that are keeping you pest-free.

Black widow female spider protecting her egg sac

Black widow female spider protecting her egg sac

Black Widow Spiders

Black widows live in dark corners in basements and garages where they spin tangled webs with which they ensnare flies, moths, and other insects. These big spiders are rare in the northern states but common in the South; there are also brown widows and a few other species that occur in the Southwest. If you live within their range, there is a fair chance you have one or two in your basement or garage; they especially love outhouses (lots of flies).

You can quickly identify a black widow by the size, shiny black legs, and characteristic red hourglass shape on the underside of the abdomen. Red and black are very common warning colors in the animal kingdom, and this mark is the spider's way of saying "stay away—I bite!" The bite of the black widow can be serious, although contrary to popular belief it is rarely fatal. If you think you have been bitten and have symptoms like stomach pain or dizziness, call 911 or get to an emergency room!

An insect vacuum like the Bugzooka is a good way to remove black widow spiders from their webs

An insect vacuum like the Bugzooka is a good way to remove black widow spiders from their webs

Control of Black Widow Spiders

If you find a black widow in your garage or basement, the best way to handle it is to get rid of the dangerous spider without killing all of the other spiders in the vicinity. Poison and other tactics may kill the black widow, but it they will kill dozens of beneficial insects as well. It's much easier, cheaper, and more respectful to remove the offending individual spider.

I have used the Bugzooka for this purpose and it works great—I didn't have to touch the spider or worry about killing other beneficial insects in my house. This solution is of course also a good one for just about any individual bug you would like to get rid of.

A house centipede

A house centipede

Brown Centipedes

You will often find these harmless creatures scuttling around in your basement, especially when you move a box they have been hiding under.

Full disclosure: I myself do not like centipedes. They have way too many legs and antennae and other appendages, and although they're basically harmless, they can bite if they have to, with pincers that are yet another pair of legs that have become adapted for the purpose.

That said, centipedes are among the most important members of your home's complimentary nighttime clean-up crew. They eat things that almost no one else would, like cockroach eggs, not to mention dead cockroaches. Along with pill bugs (roly-polys) and silverfish, centipedes are there to help. They can safely be left alone to do what they do.

bugs-in-basement

Millipedes

Millipedes are basically the centipede's mellow, slow-moving cousin. Though not closely related, millipedes and centipedes share many habits, including living in dark areas like basements. They are rounder and slower than centipedes, and their legs are little short numbers that they move in waves for locomotion.

Millipedes are a part of your home's cleaning crew, so if you find one, let it be.

bugs-in-basement

Silverfish and Firebrats

These interesting insects don't even look like insects at all—they resemble shiny little fish, hence the common name. Along with the closely related firebrat, silverfish are shy, timid creatures that come out at night to eat the gunk accumulating in your drains and pipes; this is one reason you will sometimes find one in your sink in the morning, scurrying around in a blind panic looking for a dark place to hide from you.

Like centipedes, there is no need to go after silverfish. They are helping keep your house clean, free of charge.

bugs-in-basement

German Cockroaches

Cockroaches can set up a colony in your basement, behind your fridge, or inside your walls. There are many kinds of roach (family Blattidae), almost all of them found in forests and meadows, and some of them actually quite beautiful. However the ones that trouble homeowners the most are German cockroaches, slim brown insects with leathery wings and long legs.

A cockroach infestation is not going to go away on its own, and what they say is basically true: If you see one, there are dozens you don't see. Your only real option is an exterminator, but if at all possible try to find one that will target roaches specifically, and spare all of the beneficial bugs and insects that are just living their lives in your basement and beyond.

A phorid fly, aka a drain fly

A phorid fly, aka a drain fly

Phorid Flies

Phorid flies (family Phoridae) are commonly called drain flies, because that's where you'll find them. The larvae live and feed inside drains, enjoying the gunk that builds up on the walls of pipes. Basement drains are especially susceptible to phorid flies.

You will know you have this insect in your basement if there is a cloud of tiny black flies hovering around a floor drain. They are not a terrible pest, since they don't spread disease or infest any areas you prize, but most homeowners will want to get rid of them. To do that, consider Forid drain gel, a mild pesticide that won't hurt your drin but will do a number on your drain flies.

A pill bug, rolled up for protection

A pill bug, rolled up for protection

Pill Bugs

You may know these little guys as roly-polys or sow bugs. They usually live outside, but in some cases will be found in the danker corners of your basement. They cruise around at low speed until you try to pick them up, at which point they roll up tight into a perfectly round ball until the danger—you—has passed.

Fun fact: pill bugs are actually a kind of land-based crustacean! Best to leave them alone to do their crustacean thing.

A typical little black basement bug

A typical little black basement bug

Little Black Basement Bugs

Finally, I'm including a kind of catch-all category that includes lots of different kinds of bugs that are either too fast, too small, or too plain to be easily identifiable. Call them "little black basement bugs." Most of these basement-dwelling critters will be either beetles in the family Carabidae or tiny true bugs in the order Hemiptera.

Either way, unless they fit any of the descriptions of insects above, they are probably nothing to worry about. However, if you have a lot of them, give your local university or high school science department a call and see if they can help you identify them. Good luck!

Sources

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

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