Eltham Copper Butterfly

The Eltham Copper Butterfly, Paralucia pyrodiscus lucida, has aroused considerable attention for a number of reasons. These include its rediscovery after it was believed to be extinct, its main populations occurring in small bushland patches in the middle of suburbia and its complex interaction with a plant and an ant.

Eltham Copper Butterfly
Photographer: Alan Yen / Source: Museum Victoria

Biology

The Eltham Copper Butterfly is a small, attractive butterfly that flies in summer. It belongs to the family Lycaenidae and like many other species of lycaenids, it has a close association with a group of ants; in this case, ants from a genus called Notoncus.

The butterfly larvae live within the underground nests of Notoncus, and emerge at night to feed on their food plant, Sweet Bursaria (Bursaria spinosa). The ants protect the Eltham Copper larvae while they feed, and in return it is thought that the ants feed upon secretions from the butterfly larvae. As the Eltham Copper Butterfly larvae feed only upon Sweet Bursaria, this is an example of a complex plant-butterfly-ant ecological interaction.

Conservation status

The Eltham Copper Butterfly was discovered around Eltham in 1938. It was thought to have become extinct around the 1950s, but was rediscovered at Eltham in 1986. It is now known to survive in four areas: Eltham, Greensborough, Castlemaine and Kiata. The main populations are located in the three main reserves at Eltham.

It is now listed as a threatened species under the Victorian Flora and Fauna Guarantee Act 1988. Its distribution was more widespread in the past. Numbers at the Eltham sites have declined because of loss of suitable habitat through urbanisation, and also the absence of an appropriate fire regime. Two of the reserves at Eltham were partially burnt in 1998 in order to improve the habitat for this species.