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Imperial Blue - Jalmenus evagoras
FAMILY LYCAENIDAE
This page contains information and pictures about Imperial Blue Butterflies in the Brisbane area, Queensland, Australia. The butterfly also known as Imperial Hairstreak.
- Wingspan 35mm
- The Imperial Blue butterflies are brownish blue on the top side and pale yellow with black lines on the underside. There are long curled tails on each hind wing. Females lay eggs on different kinds of wattles.
- During a sunny summer day, the male butterflies are found flying around the host plants, waiting to mate with females.
- The top view of the open-winged butterfly look like the face of a cat, hold prey with its bloody mouth. This pattern will scare most of the birds - the butterfly's predator.
- Caterpillar 40mm The caterpillar about to turn into a pupa
The caterpillars are quite common on Wattle Acacia leaves. They can easily be found during summer on the day time feeding on the leaves. The caterpillars and pupae are always attended by ants.
The caterpillars secrete a substance which the ants like. It is believed that the ants will provide protection from predators and parasitism as return. This is why the caterpillars can feed freely during the day time. The caterpillars usually pupate in group on a communal web spun among twigs.
We striped the ants away and collected two caterpillars, raised them in a jar with some fresh Wattle leaves. Without the ants protection in the wild, scientists had shown that the caterpillar will subject to parasite or predation within days.
We know that for some other blue butterfly species, the caterpillars hind during the day and rely on the ants to guide them to the food plants. This Imperial Blue caterpillar seemed living fine without those ants.
A few days later, the two caterpillars turned into pupa. The two caterpillars pupated close to each others. The Pupa are dark brown in colour.
About a week later, the Imperial Blue butterflies came out from the pupa.
The eggs of this butterfly are white to pale green in colours. The eggs are laid in rows on the stems of food plant. Female will lay eggs on different type of wattle, however, she will only choose the wattle with the right type of ants colony.
Attended by Ants
Some reference books suggested that the ants come for the honey dew produced by the special secretary organs on their body. However, we noticed that the ants also attended the pupa, which were not likely to produce any honey dew. The Caterpillars always attended by the ants Iridomyrmex sp. from the subfamily DOLICHODERINAE and not by other species of ants. We suspected that the caterpillar and pupa may exploit and take the advantage the chemical signals of those ants. The caterpillar and pupa may secrete the chemical so that the ants think they are their 'Queen' or 'sisters'. This is just a speculation that need more observations to confirm.
- Reference and Link:
- 1. Insects
of Australia, CSIRO, Division of Entomology, Melbourne University
Press, 2nd Edition 1991, p 899.
- 2. Insects of Australia and New Zealand - R. J. Tillyard, Angus & Robertson, Ltd, Sydney, 1926, p465.
- 3. Create More Butterflies - by Frank Jordan and Helen Schwencke, Earthling Enterprises, 2005, p22.
- 4. Jalmenus evagoras - Australian Caterpillars, Don Herbison-Evans & Stella Crossley, 2005.
[ Up ] - 2. Insects of Australia and New Zealand - R. J. Tillyard, Angus & Robertson, Ltd, Sydney, 1926, p465.
