Imagine waking up and seeing the morning light covering the walls of your bedroom – except for a dark shadow in one spot – that begins to MOVE! House centipedes travel at night and are frequently visible on walls, floors and ceilings. And while they have many beneficial qualities, these so-called “hundred-leggers” or “thousand-leggers” are one pretty fast and freaky bug to have to live with!
What is this bug with lots of legs?
There are two very similar bugs that are often called “hundred-leggers” or “thousand-leggers.” These are more accurately known as the house centipede and the millipede. They are both arthropods, and neither is poisonous (although some types of centipedes are) and both are pretty common throughout the United States.
To a lesser extent, the Silverfish is another insect with lots of legs but it has a distinctly different flat shape, so it’s easy to keep that one straight. The house centipede is the one most frequently thought of as the dreaded thousand legger and the one you are most likely to encounter – when you least expect it!
Meet the house centipede
The scientific name for a house centipede is Scutigera coleoptrata and can actually have between 30 and 354 pairs of legs. Surprisingly, no house centipedes have an even number of leg sets. So, you’d never find a hundred-legger with one hundred legs, let alone a thousand! House centipedes also have long legs, a long antennae and powerful jaws, that can be used to devour their prey – which thankfully consists mostly of a food source of spiders and small insects!
These so-called thousand leggers are nocturnal, preferring to do their dirty work at night. Because house centipedes love the dark, these bugs with lots of legs can be living in your house for some time. That is until you spot one some early morning that looks like it crawled right out of last night’s nightmare.
They are also a pretty prolific insect…a female house centipedes will lay eggs, sometimes 35 at a time! They also stick around for quite a while as their expected life cycle is 1 year.
Meet the millipede
Millipedes on the other hand, have more legs than the centipede. While the centipede has one per body segment, the millipede has two. That said, despite their “milli” prefix, they also don’t actually have 1,000 legs. Millipede’s don’t bite but it’s smart to avoid touching them. If you do, they’ll share with you a very foul smelling secretion as a friendly reminder of the encounter.
While the longer legged house centipede is a very fast insect, the millipede is just too cool to be motivated to do anything quickly. They take it slow, hang out in wood piles and other damp places. They enjoy a diet of decomposing plants – making them a very eco-friendly bunch!
Is the thousand-legger harmful?
The centipede that appears in houses (also called a home centipede) is not considered harmful to humans, pets, or the environment. They don’t spread disease or have noxious odors. In fact, they do have some beneficial qualities aa they’ll eat other harmful pests that may appear in the home.
According to the bug biologists at Penn State’s Extension Service, house centipedes will eat lots of insects. These include bed bugs, silverfish, firebrats, carpet beetle larvae, cockroaches, spiders, and other small arthropods.
In fact, if you have a heavy infestation of house centipedes, you can bet they are there for a reason. Look closely and you are likely to find out what other insects they are feeding on!
The thousand-legger does have venom which it uses to stun its prey, but bites to humans are rare. If it does bite a human, it is not harmful and will cause a small amount of localized pain and a little swelling at the site.
What attracts house centipedes to my house?
Besides darkness, the house centipedes like moisture and dampness. Inside your house, they are commonly found in bathrooms, attics, basements or crawl spaces, or under the kitchen sink. Keeping a basement, crawlspace or attic dry and ventilated helps to keep the pest from setting up a home.
Outside, they like trash, damp leaves, mulch, stones, grass clippings or wood piles. Take care to remove these from the foundation area of your home. If keeping a woodpile, be sure it is elevated from the ground, and away from the foundation. Cracks, crevices or holes around windows, siding or the foundation are the #1 way in which the centipede will enter your home.
Once house centipedes have taken up residence in your home, they won’t leave. They’ll usually live their entire life in your humble abode, instead of moving out with warmer weather.
How do I keep house centipedes away from my house?
OK, so now that we have you totally grossed out, here’s how to stop infestations of these creepy crawling invaders from taking up residence.
Dry out damp spaces
First if your home is damp, it’s like putting out the welcome mat for house centipedes and a host of other moisture loving bugs like termites, cockroaches and ants. Fortunately, it’s pretty easy to dry up damp areas like basements or crawl spaces under your home.
We’ve laid out step-by-step tips to fixing a damp, wet, flooded or leaking basement or crawlspace. But the bottom line is this. It all comes down three things: (1) keeping your gutters clean; (2) extending the downspouts 4 to 6 feet from the foundation and; (3) making sure that soil around the foundation perimeter of your home slopes away. Once these steps are done, a dehumidifier can help soak up any remaining dampness.
Seal gaps and cracks
Thousand-leggers are definitely the outdoorsy type. They live in damp areas like tree bark, mulch around landscaping or under piles of leaves. Because most of these conditions exist pretty close to your house, you can bet centipedes work on a way to break through your perimeter to have a look-see inside!
To keep these creatures of nature out, sealing up spaces where house centipedes can get in is a smart move. Look around for cracks, crevices or holes in your foundation. Sealing up these voids is the first thing that needs to be done to keep house centipedes away. You can use an all-weather caulk for the job.
Best insecticide for centipedes
Also, use an indoor caulk on cracks around baseboards or quarter rounds should be used. The stealthy house centipedes will hide in those cracks and crevices under the wood trim. Spray foam insecticide comes with a straw-like applicator and can be helpful to get in small outside spaces. It will seal up the holes, and not allow the household pests to actually enter your house!
If you don’t think you have an infestation, just vacuum up any you see. However, dispose of the dirt in the vacuum so they don’t have a chance to re-infest your home. If you spot more than a few pests an insecticide spray can be used to eradicate them. It can be used outdoors as well as indoors. A perimeter spray around your house, and spraying baseboards or other suspected hiding places is prudent.
One other product that is most commonly used to kill house centipedes in attics is an insecticidal dust. Just be sure to follow the directions of the manufacturer as to application, usage, and safety for humans and pets.
Hire a pest control pro to evict home centipedes
If you have tried, but still are seeing “thousand-leggers” you may need to call a professional pest control service for the job. You will most likely pay more, but most pest control companies guarantee their work. Plus, these licensed exterminators are also able to use products not available to the general public. The pesticides they’ll use are very targeted to the specific insect they are treating, and highly effective.
No matter what you call them, house centipedes, hundred-leggers or thousand-leggers – these bugs can definitely cause plenty of frightening encounters in your home. The good news is that they won’t cause you or your home any harm. By following these tips, you’ll get the peace of mind and eliminate this pest in the home.