The term “potato bug” is a common name used to describe two distinctly different insects: the Colorado Potato Beetle and the Jerusalem Cricket. These insects have little in common beyond their occasional presence near potato plants. A correct identification requires understanding their varied physical characteristics and behaviors, as they look nothing alike.
The Striped Colorado Potato Beetle
The Colorado Potato Beetle (Leptinotarsa decemlineata) is a small, oval-shaped insect most often associated with the name in agricultural settings. The adult beetle measures between 6 and 11 millimeters (about 3/8 inch) in length, featuring a rounded, convex body shape. Its head and thorax are yellowish-orange, often marked with small black spots.
The most defining feature is the pattern on its hardened forewings (elytra). The yellowish-white elytra are each marked with five bold black stripes running lengthwise down the back. This results in a total of ten black stripes, a feature reflected in its species name, decemlineata, which means “ten-lined.”
The body structure follows the typical beetle form, with a small head connected to a slightly larger thorax, followed by the large, striped abdomen covered by the elytra. The overall appearance is bright and easily visible against green foliage. This striped adult form is what most people picture when they think of a classic garden pest.
The Wingless Jerusalem Cricket
The insect also called a “potato bug” in the Western United States is the Jerusalem Cricket, belonging to the genus Stenopelmatus, a creature that is neither a true cricket nor a beetle. This insect is substantially larger than the Colorado Potato Beetle, often reaching lengths of 2 to 3 inches, giving it a stout and intimidating appearance. Its body is robust, thick, and wingless, lending it a segmented, almost prehistoric look.
The Jerusalem Cricket’s most striking feature is its disproportionately large, bulbous head, which is smooth and often described as having a human-like or bald appearance. The head is typically brownish or amber-colored, bearing strong mandibles that are capable of delivering a defensive bite if the insect is handled. Its abdomen is rotund and shiny, displaying a pattern of alternating brown and black bands or stripes.
This insect is flightless, and its legs are short, thick, and noticeably spiny, specifically adapted for digging in the soil. The Jerusalem Cricket lacks the slender profile and long hind legs typical of true crickets like the common field cricket. The combination of its large size, massive head, and lack of wings makes its visual identification distinct from any beetle.
Identifying Based on Habitat and Activity
Observing where and when the insect is found provides the fastest way to confirm its identity without relying solely on physical features. The Colorado Potato Beetle is a pest of cultivated plants and is almost exclusively found above ground and on foliage. Adults and their larvae spend their time openly feeding on the leaves of plants in the nightshade family, particularly potatoes, tomatoes, and eggplants.
The adult beetles are active during the day and can be observed walking on stems or sometimes flying to new host plants, especially when temperatures are warm. A secondary identifier for the beetle’s presence is the bright yellowish-orange egg clusters, which are typically laid in groups of 20 to 50 on the underside of plant leaves. The beetle’s life cycle is centered around the plant, where it defoliates leaves before the mature larvae drop to the soil to pupate.
Conversely, the Jerusalem Cricket is a subterranean creature that spends the vast majority of its life underground, burrowing in loose or sandy soil. These insects are strictly nocturnal, meaning they are active only at night, emerging from their burrows under rocks or logs to forage for food. They are not typically seen on plant foliage and are instead known to consume roots, tubers, and decaying organic matter found in the soil.
While the beetle communicates visually and chemically, the Jerusalem Cricket uses a unique form of communication involving vibrations. To locate a mate, both males and females create a characteristic “drumming” sound by repeatedly striking their abdomen against the ground. This behavior confirms the identity of the Jerusalem Cricket through sound and activity, as the drumming travels through the soil and is not a sound produced by the Colorado Potato Beetle.