Large Blue caterpillars feed on wild Thyme flowers for the first few days of development. Afterwards, they seek out the nests of a specific species of red ant, and hibernate inside their tunnels. On emerging from hibernation, the caterpillars will then begin to eat the red ant's eggs and larvae for up to 3 weeks. It will then hang itself by its legs on the nest's roof and build a chrysalis around itself. The caterpillar will spend a further 3 weeks transforming into the Large Blue butterfly adult. After its change from caterpillar to butterfly, the insect emerges from its chrysalis and leaves the red ant nest to find a mate. Usually, red ants will escort the newly emerged butterfly to the surface, taking it to a low plant or shrub nearby. The red ants will encircle the butterfly and ward off any predators that attempt to attack the butterfly as it dries out. After the butterfly is ready to fly away, the ants will retreat back into their nest.