Fats and oils primarily and proteins as secondary
Bigheaded ants nest in colonies underground. Colonies can have several queens and super-colonies can be formed by budding; when a queen and workers leave the original nest and set up a new colony nearby without swarming. In America, for example, nuptial flights of winged ants take place during the winter and spring and afterwards, fertilized queens shed their wings and find a suitable site to create a new colony where they start laying eggs. Each queen lays up to 290 eggs per month. The eggs hatch after two to four weeks and the legless white larvae, which are fed by the workers, pupate about a month later. The adult workers emerge ten to 20 days after that.
The bigheaded ants feed on dead insects, small invertebrates and honeydew excreted by insects such as aphids, soft scale insects, mealybugs, whiteflies and planthoppers. These sap-sucking bugs thrive in the presence of bigheaded ants, being more abundant on plants patrolled by ants than on those not so patrolled. Green scale, Coccus viridis, numbers peaked when coastal brown ants protected their food source by removing predators such as lady beetle larvae and lepidopteran larvae. The minor workers are much more numerous than the soldiers. Trails of ants lead up trunks, along branches and into the canopies of trees and debris-covered foraging tunnels with numerous entrances are created on the surface of the ground. These may be confused with similar tubes built by subterranean termites. Foraging ants will alert others to new food sources. Honeydew is ingested whilst both major and minor workers who may transfer items of food between themselves carry other foodstuffs back to the nest. Anything too big to be moved may be dissected before being brought back to the nest.