Mystery solved

One of the frustrations when walking in the bush is when you see an interesting thing but don’t have enough data to work out what it is. And so it was walking back to the house at dusk I came across a Silver Wattle (Acacia dealbata) in which was attached two butterfly (or moth) pupae covered in ants. A subsequent keyword search in Google got me no closer to understanding what I had seen. The return trip next day to get some photos revealed several nearby trees festooned with ant covered pupae. And on one of the branches was a recently emerged butterfly, one that I had never seen before, EVER. Back to the books — it was problem solved.

The butterfly was an Imperial Hairstreak (Jalmenus evagoras). A small sized butterfly (pictured above), it is found on the east coast of Australia from southern Queensland along the Great Dividing Range to Victoria. It is of the Lycaenidae family of butterflies, which is known to have relationships with ants. In summer after mating this female butterfly flies around looking for a suitable place to lay eggs. The eggs are only laid on certain acacias; Silver Wattle is one of them. The other prerequisite is that of the 3000 species of Australian ants, the eggs have to be laid near populations of either of two of these species, Iridomyrmex anceps or I. rufoniger.

After hatching the ants tend the caterpillars (pictured right) and later the pupae, both of which excrete honeydew, a food source for the ants. In return the ants protect against predators such as wasps and spiders. It is this protection that allows the caterpillar to feed during the daytime and the pupae to hang in plain view. The caterpillars pupate in a group on a communal web (pictured below).

The Imperial Hairstreak is rarely seen. It flies at grass height and with its wings closed it is highly camouflaged. The open wings reveal bright, iridescent blue patches.

So if you are walking in the bush and you see flashes of blue, you have probably disturbed one of these beautiful butterflies … or if you are walking to your ‘plot’ it’s probably the police.