The term “doodle bug” is a common name for two entirely different animals with contrasting diets: the Antlion Larva and the Pill Bug, also known as the Roly-Poly. The Antlion Larva is a dedicated predator, while the Pill Bug is a detritivore. Understanding the diet of a “doodle bug” requires distinguishing between these two creatures, as one hunts live prey and the other consumes decaying matter.
The Antlion Larva’s Prey
The Antlion Larva is an ambush predator with a diet consisting exclusively of live arthropods. Its primary food source is ants, but it consumes any small crawling insect that falls into its sand trap, including spiders, mites, and small beetle larvae. The size of the prey captured is directly related to the size of the larva and its pit.
The larva remains buried at the bottom of its conical pit, waiting for a victim to stumble over the edge. The sides of the trap are engineered with loose sand, causing the prey to slide toward the center. If the prey attempts to climb out, the antlion flicks sand, creating miniature landslides that ensure the insect tumbles back down.
The Pill Bug’s Preferred Food
The Pill Bug (Roly-Poly) is a terrestrial crustacean that functions primarily as a decomposer. As a detritivore, its diet centers on dead and decaying organic matter, or detritus, which includes rotting leaves, dead wood, and soft, decomposing plant material. They play an important role in recycling nutrients by breaking down plant litter, thereby enriching the soil.
Pill bugs seek out specific nutrients, preferring fungi, algae, and animal droppings. They consume their own waste (coprophagy) to reabsorb copper and other nutrients. While they prefer dead material, large populations may occasionally nibble on soft roots, seedlings, or ripe fruits that contact the ground, especially during periods of low moisture. They obtain necessary calcium from sources like old shells.
Capturing and Consuming Food
The Antlion Larva and the Pill Bug employ entirely different biological tools to acquire and ingest their food, reflecting their contrasting diets. The antlion secures its prey using massive, sickle-shaped mandibles that are hollow and permanently fused to the maxillae.
These specialized jaws are used to inject a paralyzing venom and digestive enzymes into the victim. This process, known as extracellular digestion, liquefies the prey’s internal tissues, allowing the antlion to suck out the nutrient-rich fluid.
Conversely, the Pill Bug uses robust chewing mouthparts to process solid food. They possess mandibles designed to physically break down tough organic matter like bark and decaying leaves into ingestible pieces.
This mechanical breakdown of detritus is a necessity for their role as decomposers to access the embedded nutrients. Once the antlion has finished its liquid meal, it flicks the dry, empty husk of the carcass out of its pit. The pill bug leaves behind partially digested matter that is further broken down by soil microbes.