Curiosity about the natural world often leads to questions about the small creatures sharing our environments. Among these, the term “potato bug” frequently surfaces, prompting inquiries into its identity and characteristics. This common name, however, can refer to more than one type of creature, leading to confusion about what exactly a “potato bug” is and how many legs it might possess.
The Leg Count Revealed
The number of legs a “potato bug” has depends entirely on which creature the common name refers to.
If the term describes a pillbug or sowbug, these arthropods have 14 legs. As terrestrial crustaceans, they have more legs than typical six-legged insects.
Conversely, if “potato bug” refers to the Colorado potato beetle, the leg count is six. As a true insect, it has three pairs of legs. The ambiguity of the common name “potato bug” highlights the importance of precise identification when discussing these diverse organisms.
Unpacking the “Potato Bug” Identity
The two primary creatures commonly called “potato bugs” are biologically distinct: pillbugs/sowbugs and the Colorado potato beetle.
Pillbugs (Armadillidium vulgare) and sowbugs (Porcellionidae) are land-dwelling crustaceans, more closely related to shrimp and lobsters than to insects. They possess a segmented, oval-shaped body, typically dark gray, and are known for their ability to roll into a tight ball when disturbed, a defense mechanism, especially for pillbugs. These crustaceans primarily feed on decaying plant matter, acting as detritivores in their ecosystems.
The Colorado potato beetle (Leptinotarsa decemlineata), however, is a true insect, a type of leaf beetle. Adults are easily recognized by their yellowish-orange bodies with ten distinct black stripes running lengthwise down their wing covers. This beetle undergoes complete metamorphosis. Both its larvae and adults are herbivorous, with a particular preference for potato plants.
Life in Their Habitat
Pillbugs and sowbugs thrive in moist, dark environments, often found beneath rocks, logs, leaf litter, and in gardens. They breathe through gill-like structures, requiring a damp habitat to breathe. These nocturnal creatures play a significant role as decomposers, breaking down organic material and returning nutrients to the soil, improving soil quality. While generally beneficial, they may occasionally feed on tender seedlings or fruits that touch the soil if other food sources are scarce.
The Colorado potato beetle inhabits agricultural fields where host plants like potatoes, tomatoes, and eggplants grow. Both the adult beetles and their larvae are voracious feeders on the foliage of these plants, capable of causing substantial defoliation and yield loss to crops. Adults can fly, allowing them to disperse to new fields. The beetle overwinters as an adult in the soil, emerging in spring to feed and lay eggs on the undersides of host plant leaves.