Ants are social insects with a complex division of labor that makes them significant decomposers and scavengers within various ecosystems. They constantly recycle organic matter back into the environment. When a dead fly or another insect is encountered, ants will consume it. This behavior is a common and opportunistic strategy for colony sustenance, driven by the colony’s nutritional requirements.
The Core Answer: Necrophagy in Ant Colonies
The consumption of dead or decaying flesh, a behavior known as necrophagy, is a widespread feature of ant foraging. For an ant colony, dead insects, including flies, represent a concentrated and easily obtainable food source. This resource requires no expenditure of energy on pursuit or struggle. Scavenging is a reliable way to supplement the colony’s diet, especially when live prey is scarce or difficult to subdue. Different ant species regularly engage in this practice, reinforcing that a dead fly is a valuable prize.
The Role of Protein and Nutrients
The primary motivation for consuming dead insects is the colony’s need for protein. Protein, abundant in the tissues of a dead fly, fuels the growth and development of the colony’s brood (eggs, larvae, and pupae). Adult worker ants rely mostly on carbohydrates, such as sugars and nectar, for their energy. They ferry the protein-rich material back to the nest to feed the queen for egg production and to nourish the non-foraging larvae. A dead fly serves as a high-quality source of amino acids and fats, essential for raising the next generation of workers. Foraging ants prioritize protein when the larval population is high.
Processing the Meal: Transport and Dismemberment
When a solitary scout ant locates a dead fly, it initiates resource processing. The scout returns to the nest while laying a chemical trail using pheromones to recruit nestmates to the site. Cooperative transport is often necessary for a large item like a fly, requiring multiple workers to drag the carcass back to the nest entrance. If the food item is too large to move efficiently, workers resort to dismemberment at the site itself. Ants use their mandibles to break down the tough outer shell, or exoskeleton, composed of chitin. They tear the fly into smaller, manageable pieces that are easier to carry. Once fragments are brought into the nest, they are processed further into a digestible slurry before being fed directly to the larvae.
Beyond Flies: The Broader Ant Diet
Scavenging dead flies and other insects is only one component of the broader ant diet, as most species are omnivorous. Adult worker ants primarily seek out carbohydrates from sources like flower nectar, sweet plant secretions, or honeydew excreted by sap-sucking insects. This sugar provides the quick energy needed for foraging and colony maintenance. Ants also exhibit a wide range of other specialized foraging behaviors. Some species are active predators, hunting live insects, while others are granivores, collecting and storing seeds. Leaf-cutter ants, for example, use collected plant matter to cultivate a fungus garden, which is their actual food source. Scavenging remains a universal, opportunistic strategy.