Red imported fire ants (Solenopsis invicta) are an invasive species widespread across the southern United States and other regions. Known for their aggressive nature and rapid colony establishment, understanding their diet is crucial to comprehending their survival strategies.
The Diverse Diet of Red Fire Ants
Red fire ants are highly opportunistic omnivores, consuming both plant and animal matter, which allows them to thrive in various environments. Their diet includes a wide array of insects and other arthropods, serving as a primary protein source. They prey on caterpillars, crickets, ticks, spiders, earthworms, and even other ant species.
Beyond invertebrates, fire ants also consume plant material like seeds, young seedlings, and parts of mature crops such as corn, sorghum, and soybeans. They are known to feed on nectar, pollen, and honeydew, a sugary excretion produced by sap-feeding insects like aphids. These ants will tend to aphid colonies, protecting them in exchange for this carbohydrate-rich substance.
Their diet extends to small vertebrates, including newly hatched birds, reptiles, and rodents, especially when vulnerable in their nests. Fire ants also scavenge, readily feeding on carrion or human-related foods like fats, proteins, and sugary substances found in food scraps and pet food.
Foraging and Food Processing
A distinct difference exists in the diet of adult fire ants and their larvae. Adult worker ants are anatomically limited to ingesting liquids, as their mouthparts cannot process solid particles larger than approximately two microns. Conversely, larvae, particularly in their fourth developmental stage, are capable of digesting solid food. This unique role means larvae process solid food for the entire colony.
Fire ants employ sophisticated strategies to find and process food. Scout ants venture out to locate food sources. Upon discovery, a scout lays a pheromone trail on its return to the colony. This chemical signal, produced by the Dufour’s gland, recruits nestmates to the food source.
When a food source is located, numerous ants follow the pheromone trail to transport the item back to the nest. If too large, workers dismantle it into smaller pieces. This cooperative transport allows the colony to efficiently exploit resources.
Within the nest, a communal feeding system distributes nutrients throughout the colony. Solid food brought back by foragers is given to the oldest larvae, typically those in their fourth instar. These larvae secrete digestive enzymes onto the solid food, liquefying it before ingesting it. The larvae then regurgitate this nutrient-rich liquid, which is consumed by adult worker ants. This process, called trophallaxis, involves the mouth-to-mouth transfer of food among colony members, creating a shared “communal stomach” for the entire colony.