The common name “potato bug” is used across the United States to describe several distinct species, causing confusion about whether the creature is harmless or a serious pest. This term refers to three primary, biologically different groups of organisms, each posing a different level of threat to people and gardens. Understanding these differences is necessary for effective management. This article clarifies the identity of the various “potato bugs” and assesses the risks they pose.
Identifying the Real Potato Bug Candidates
Accurate identification is required due to the ambiguity of the term “potato bug.” The Pill Bug, or Roly-Poly, is a terrestrial crustacean. These small, gray creatures measure about half an inch and are characterized by their segmented, armor-like shell. They can roll into a tight, protective ball when disturbed. Pill bugs are found globally and thrive in moist, dark environments like under rocks and decaying matter.
The Colorado Potato Beetle (Leptinotarsa decemlineata) is a serious agricultural pest. Adult beetles are oval-shaped, about three-eighths of an inch long, with yellowish-white wing covers marked by ten black stripes running lengthwise. Their larvae appear slug-like with pink or red bodies and two rows of black spots along the sides. This beetle is native to the Southwestern U.S. and Mexico but has spread worldwide, posing a threat to certain crops.
The Jerusalem Cricket (Stenopelmatus spp.) is a large, wingless insect found in the western United States. These crickets are stout, up to two inches long, with an oversized, pale, or brownish head and black bands on the abdomen. They are nocturnal burrowers that use powerful forelimbs and strong mandibles for subterranean movement. They communicate by drumming their abdomen against the ground.
Physical Threats to People and Pets
The creatures known as potato bugs pose minimal physical risk to humans and domestic animals. Pill Bugs are harmless; they do not bite, sting, or carry diseases. These crustaceans rely on rolling into a ball for defense and are considered nuisance pests only when they seek moisture indoors.
The Colorado Potato Beetle presents no direct physical threat to mammals. They are not aggressive and lack the means to bite or sting. Their bodies contain toxic alkaloids, but this poses a threat only if ingested in large quantities, which is unlikely for humans or pets. The beetle’s harm is focused entirely on plant life.
The Jerusalem Cricket is the only one capable of inflicting a painful injury, though it is not venomous. Their large mandibles can deliver a defensive bite, which may cause localized pain, redness, and swelling. These bites are not medically significant and heal without lasting effects, as the insects are not aggressive and prefer to retreat.
Impact on Gardens and Agriculture
The Colorado Potato Beetle causes significant defoliation to plants in the nightshade family (Solanaceae). Both the adult beetles and the larvae consume plant foliage. The fourth larval instar is responsible for up to 75% of the total feeding damage. Uncontrolled infestations can lead to complete defoliation of potato plants, reducing tuber yield and quality.
Pill Bugs consume decaying organic matter, helping to cycle nutrients back into the soil. They become a nuisance pest only when their populations swell and they begin to feed on tender live plant tissue. This damage is usually limited to young seedlings or fruits resting on the ground, mainly when decaying matter is scarce.
Jerusalem Crickets are omnivores that primarily scavenge on decaying plant material and other insects. Their burrowing and feeding habits can occasionally damage garden plants by chewing on roots and tubers. While they are not considered a major agricultural pest, their presence can be problematic where root vegetables are grown.
Prevention and Safe Removal
Control methods for the Colorado Potato Beetle include:
- Handpicking adults and larvae and dropping them into soapy water, which is practical for small gardens.
- Regularly inspecting the undersides of leaves to crush the clusters of yellowish-orange eggs before they hatch.
- Using floating row covers as a physical barrier to prevent adult beetles from landing and laying eggs on susceptible plants.
The most effective prevention for Pill Bugs involves modifying their habitat by reducing damp, sheltered areas. This means clearing away excess mulch, leaf litter, and plant debris from garden beds and around foundations. If populations are high and damaging seedlings, using diatomaceous earth around vulnerable plants or setting shallow traps with fruit rinds can help manage their numbers.
Jerusalem Crickets are best managed by exclusion and habitat modification. Sealing cracks and crevices around the foundation of homes can prevent them from seeking shelter indoors. In the garden, minimizing objects like boards or stones that provide dark, moist hiding spots can discourage their presence. If one must be removed, it is best to use a glove or a tool to avoid a defensive bite.