Ants and “roly polies,” formally known as pillbugs (or woodlice), are common invertebrates encountered in shared outdoor environments. These creatures inhabit similar moist, shaded habitats, often found beneath rocks, logs, or decaying leaf litter. Their frequent proximity often leads to questions about their ecological interactions, particularly whether ants view pillbugs as a food source.
The Direct Answer
Ants do not typically eat pillbugs as a primary or preferred food source. Pillbugs possess several defensive mechanisms that make them unappealing prey. Their tough, segmented exoskeleton provides a physical barrier that is difficult for most ants to penetrate. When disturbed, pillbugs exhibit a behavior called conglobation, rolling into a tight, protective ball that shields their softer, vulnerable undersides.
Beyond physical defenses, pillbugs also have chemical deterrents. They possess repugnatorial glands that release unpleasant secretions. These secretions, which contain uric acid, can give pillbugs an unpalatable taste. While most ants avoid them, predation by ants is rare and usually limited to specific circumstances, such as extreme starvation, or if the pillbug is already injured or molting. A few specialized ant species, like Leptogenys, have evolved elongated mandibles capable of prying apart conglobated pillbugs.
Ant Feeding Habits
Ants are largely omnivorous and opportunistic feeders. Their diet is diverse and varies significantly among different species, but it generally includes both carbohydrates for energy and proteins for growth and development. Worker ants require carbohydrates to fuel their foraging activities and maintain the colony.
Common carbohydrate sources for ants include sugary substances like honeydew, which is secreted by aphids, as well as nectar, fruits, and tree sap. Proteins are important for the queen and developing larvae, supporting their growth. Ants obtain protein from other insects, insect eggs, small invertebrates, and carrion. Some ant species, like harvester ants, specialize in collecting seeds, while others cultivate and consume fungi. Ants locate food by laying down chemical scent trails, known as pheromone trails.
Pillbug Characteristics and Diet
Pillbugs are not insects; they are terrestrial crustaceans, making them more closely related to shrimp and lobsters than to ants. Their segmented bodies are covered by a rigid exoskeleton. Pillbugs breathe using gill-like structures, which necessitates their reliance on moist environments to absorb oxygen.
A defining characteristic of many pillbugs is their ability to roll into a compact ball when threatened, a defense mechanism known as conglobation. This action protects their softer underside. Pillbugs also produce unpleasant chemical secretions from specialized glands, deterring potential predators. As detritivores, pillbugs primarily feed on decaying organic matter, playing a significant role in decomposition. Their diet consists mainly of dead leaves, rotting wood, fungi, and other plant debris, which helps recycle nutrients back into the soil. While they generally consume decaying material, they may occasionally eat tender living plants like seedlings or overripe fruits if other food sources are scarce.