“Potato bug” in Ohio almost always refers to one of two creatures: the Colorado potato beetle, a striped garden pest that destroys vegetable crops, or the pillbug (roly-poly), a gray armored crustacean that curls into a ball when disturbed. Both are common across the state, but they look nothing alike, cause very different problems, and require completely different responses. Here’s how to figure out which one you’re dealing with and what to do about it.
Two Very Different Bugs, One Name
The Colorado potato beetle is a true insect with three pairs of legs, an oval body about 3/8 inch long, and distinctive yellowish-white wing covers marked with 10 narrow black stripes. Its head area is yellow-orange. If you see bright yellow or orange egg clusters on the undersides of your potato or tomato leaves, this is your culprit.
Pillbugs, on the other hand, are not insects at all. They’re land-dwelling crustaceans, more closely related to shrimp than to beetles. They have seven pairs of legs, a segmented shell-like covering, and that signature ability to roll into a tight ball. Sowbugs look nearly identical but can’t curl up and have two small tail-like projections. Both are slate gray, roughly half an inch long, and live in damp soil, mulch, and leaf litter.
If your “potato bug” is on a plant and has stripes, it’s a Colorado potato beetle. If it’s under a rock, in your mulch, or curled into a ball on your basement floor, it’s a pillbug.
Colorado Potato Beetle: Ohio’s Real Garden Threat
Ohio gardeners deal with Colorado potato beetles every summer, and OSU Extension has flagged them as a recurring problem across the state. These beetles feed primarily on potatoes but will also attack eggplant, tomatoes, and peppers, all members of the nightshade family. A single adult can eat about 10 square centimeters of leaf per day, roughly the area of one and a half playing cards. That sounds modest until dozens or hundreds are feeding at once.
The larvae do even more damage than the adults. They hatch from those bright yellow-orange egg clusters on the undersides of leaves and go through four growth stages. Early-stage larvae are brick red with black heads. As they mature, they turn pink to salmon colored, still with black heads and two rows of dark spots along each side. These large, late-stage larvae move actively across the plant and are the most destructive phase. Unmanaged infestations can strip a plant completely bare, and total defoliation means dramatically reduced potato yields or no harvest at all.
When They Appear
Adults overwinter in the soil and emerge in late spring as potato plants begin to grow. They mate, lay eggs, and the first wave of larvae hatches within a couple of weeks. In Ohio, heavy feeding typically peaks in June and early July. Depending on conditions, a second generation can appear later in the summer, extending the damage window into August.
How to Control Them
The most effective time to act is during the larval stage, right as egg masses are hatching and young larvae begin feeding. OSU Extension recommends timing any treatment to this window rather than waiting until large larvae have already caused significant defoliation. Here’s a practical approach:
- Hand-picking: For small garden plots, checking plants every few days and removing adults, egg clusters, and larvae by hand is surprisingly effective. Drop them into a bucket of soapy water.
- Crop rotation: Don’t plant potatoes, tomatoes, or eggplant in the same spot year after year. Adults emerge from the soil where last year’s crop grew, so even moving your potatoes to the opposite end of the garden helps.
- Row covers: Lightweight fabric barriers placed over plants in spring can prevent adults from reaching the foliage to lay eggs in the first place.
- Targeted sprays: Organic options containing a naturally occurring soil bacterium are effective against young larvae while being gentler on beneficial insects. Conventional insecticides work too, but Colorado potato beetles are notorious for developing resistance, so rotating between different types is important.
Pillbugs: Mostly Harmless Recyclers
If what you’re finding are gray, armored, multi-legged creatures in your garden beds, under pots, or inside your basement, you’re looking at pillbugs or sowbugs. These are overwhelmingly beneficial. They break down dead plant material and return nutrients to the soil. They don’t bite, they’re not venomous, and they pose no health risk to you or your pets.
Occasionally, pillbugs will nibble on tender seedlings or strawberries resting on damp soil, but this is far less common than gardeners assume. Before treating for pillbugs, it’s worth going out at night with a flashlight to confirm they’re actually the ones causing damage, since they feed after dark and the real culprit is often slugs or other pests.
Reducing Pillbug Numbers
Because pillbugs need constant moisture to survive (they breathe through gill-like structures), managing moisture is the most effective control method. Pull back excess mulch, grass clippings, and leaf litter from around your plants. Avoid overwatering your garden beds. Elevate flower pots and planters so air can circulate underneath. Remove lumber, rocks, and debris stacked near your home’s foundation, since these create the cool, damp microhabitats pillbugs seek out.
If large numbers are getting inside your house, the fix is almost always sealing entry points (gaps under doors, cracks in the foundation) and reducing moisture near the exterior walls. Pillbugs that wander indoors typically die within a day or two because the air is too dry for them.
Are Potato Bugs Dangerous?
Neither the Colorado potato beetle nor pillbugs pose any danger to people. Colorado potato beetles don’t bite, sting, or carry diseases. They’re purely a crop pest. Pillbugs are equally harmless to humans.
There’s a third insect sometimes called a “potato bug” that occasionally causes confusion: the Jerusalem cricket, a large, bald-headed, cricket-like insect found mainly in the western United States. Jerusalem crickets are not established in Ohio, so if you’re in the state, you’re almost certainly dealing with one of the first two. For the record, Jerusalem crickets are also non-venomous, though their size (up to two inches) and strong jaws mean they can deliver a painful bite if handled roughly.