It’s become one of my annual rituals.
Each year, post Xmas, I pay a visit to a stand of Silver Wattles near Yandoit.
They are home to a colony of Common Imperial Blue Butterflies Jalmenus evagoras aka the Imperial hairstreak or simply the Imperial blue.
In common with many Australian butterflies this species has a fascinating and complex life history, of which Iridomyrmex ants play a key part. The larvae of this butterfly feed on the foliage of numerous species of acacias, locally I’ve only found them on Silver Wattle Acacia dealbata. The ants live in underground nests and emerge to provide protection for the caterpillars from predators and parasitoids. The reproductive success of the butterfly is significantly improved from this protection, meanwhile the ants profit from supping on sugary secretions produced by the larvae.
On most recent visits to the colony the adult butterflies have kept their wings folded. Yesterday however, was a cool morning and the butterflies were warming up – fully opening their wings to absorb the rays of the sun, displaying the brilliant metallic blue from which J.evagoras gets its common name.