Centipedes and Millipedes

Q. I need a safe, effective way to get rid of centipedes and/or millipedes. (Not sure which I have.) They wander upstairs sometimes—ick!—so it's an emergency! It must be non-toxic. I would appreciate any suggestions. Thanks!

---Laurie in Royal Oak, Michigan

A. Centipedes tend to be tan in color, long-legged, look kind of like a dropped toupee, move very fast, and are rarely found in large numbers. Millipedes are thinner and rounder with many small legs, generally black in color, curl up when threatened, stink when crushed, and can appear in overwhelming numbers when Spring is overly wet, as they are creatures of moisture. Which do you have?

Q. We have centipedes. I run a dehumidifier and we don't see big bunches; they show up one at a time right at bedtime, making our daughters get all upset. (I'm not crazy about them, but the girls are terrified.) I always thought they didn't actually live inside the house and just came in from outside. Is it true they eat spiders? And what should I do?

---Thanks again, Laurie

A. How about nothing? The house centipede (which is an indoor creature in the North, but mostly an outdoor dweller down South, despite its name) is a highly beneficial household helper, eating lots of fleas, ants, flies, silverfish, roaches, ticks and other pests. Forget about using insecticides against them, they ARE insecticides! Get rid of your centipedes and you will almost certainly increase the number of TRUE indoor pests in your home.

…Which most spiders, by the way, are not. Visible indoor spiders are harmless to humans, but deadly to pest insects. The only spiders that are dangerous to people are the legendary black widow, which lives outside in places like old wood piles; and the recluse spiders, which as their name implies, stay hidden all the time (and appear in a very limited geographic area in the US). If you see big scary-looking spiders in your home (like the fabulous wolf spider) they are totally beneficial.

If your girls are young, explain that, like ladybugs, centipedes are our protective friends. If they scream "I don't care" and threaten to flush their Winnie the Pooh bedtime pal down the toidy, use a little hand vac and suck the centipedes up, or use a broom to knock them into a paper bag. Then release them into the garden, where they can continue to live their long, remarkable lives—they can live as long as five or ten years—eating pests out there.

Just don't complain if your house gets buggy.

Q. Mike, I'm a recent transplant from Boston and find gardening down here to be a veritable Eden-like experience. The soil is miraculous and the climate intoxicating for plants and wildlife. It's that second thing I'm writing about—a creature I never saw before I moved here that I believe is known as a millipede. Their distinguishing characteristics seem to be 1) an ability to get anywhere in my house, including THE BEDS on the second floor, causing no end of angst in my children; and 2) a repugnant smell when you squish them. I thought I heard you say they only infest moist houses, but ours is air-conditioned with dehumidifiers in the basement and upstairs. But I'm still trying to learn how to live in the soup you call air here in the mid-Atlantic, and maybe I need to learn further dehumidifying techniques. Thanks so much for your guidance.

---Laura in Wynnewood, Pa.

Can you please tell me what I can do to get rid of millipedes? They are in the thousands!

---Mandy in Old Washington, AR

A. Ah yes, the crush and sniff test. If that little black wormy guy smells like condensed cream of old gym socks when you step on him, you got millipedes. Outdoors in the garden, these creatures are 50/50; they aerate the soil and help break down organic matter, which is good, but experts warn that they will also sometimes attack young seedlings and fruits lying on the ground, like strawberries. The seedling part may well be true, but I think they only go after fruits when other creatures, like the noble slug, have already done some damage.

Indoors however, they are pure—a pure pain in the butt! Other than warning that your house is damp, they serve no purpose, and can show up in very disturbing numbers. Dehumidifiers and air conditioners are a good start, but may not be enough if your house is really damp. And when Spring is saturatingly wet, even multiple dehumidifiers can't keep up. So get some hydrometers (that's the fancy name for humidity indicators, like on those temperature, humidity and barometric pressure combos) and see how humid you are. If its 50% or above, you're damp.

You may have to do some work outdoors to alleviate the problem. Make sure rainwater is diverted far away from the house by extended gutters, and that rains are not allowed to come pouring into your cellar from something like a hill behind the house. Wait till Spring and cut back shrubbery overly close to the house so that air can circulate in between; your plants will appreciate it as well.

You should wait until Spring because it can be very damaging to prune plants in the Fall; prune NOTHING in the fall that isn't dead or heavily diseased. If the tree canopy overhead is denser than I am my first day back after a long vacation, have some branches thinned out over the winter (that's the best time to trim big trees).

If a multitude of millipedes still appears, sweep large numbers up with a broom or suck them up with a shop vac. Their name can be legion, so you may have to do this repeatedly. Be brave; their numbers WILL decrease.

When you've gotten rid of enough that you can at least see the floor again, spread diatomaceous earth ("DE", a mined powder composed of the fossilized remains of ancient sea dwelling creatures that's sold to control slugs) or the dry form of boric acid, often labeled "roach powder". Both of these desiccating dusts will dehydrate creatures what encounter them. They are not dangerous in the chemical way, but you should always wear a dust mask when you apply any dusty substance.