The fire ant queen continues to lay eggs throughout her life. She can live up to 7 years and produces an average of 1,000 eggs each day. The eggs hatch into white, legless, grub-like larvae that are fed by the workers.
The fire ant larvae develop through four progressively larger stages called instars. They molt (shed their “skin”) between stages. The worker ants feed solid food to the oldest larvae (last instar). Only these last instars digest the food, then secrete a nutritious liquid that the workers feed on and pass to the queen through trophallaxis.
The last larval instar becomes a pupa. Instead of spinning a cocoon (like a caterpillar or a spider), the fire ant larva sheds its outer skin to reveal an ant-like form that gradually changes from white to brown. Pupae do not eat, but slowly develop into an adult ant that emerges from the pupa. The size of the larvae depends on what their ultimate form will be. Fire ant worker larvae are relatively small; future queens and males (known as winged “reproductives”) develop from larger larvae. All worker ants in the colony are females that sting but cannot lay eggs.
Photo right: Larvae (top row) and pupae of minor, major and winged reproductive castes (bottom row) of imported fire ant. Note: there are four developmental stages or instars of larval development (only three are shown) between molts with the last stage molting into a pupa.