(Photo: courtesy of Merlin Crossley)
Don Herbison-Evans (
donherbisonevans@yahoo.com )
&
Stella Crossley
(updated 4 July 2004)
Caterpillars of this species are semi-loopers because some of their ventral prolegs are reduced and this makes them move looper fashion, like the caterpillars of GEOMETRIDAE.
The caterpillars are green with a darker green line along the back, bordered by two light stripes. Their sides are marked with white parallel lines, and sometimes a row of black spots.
Caterpillars reared from the same batch of eggs differ in their degree of spotting. Each spot is actually at the base of a hair. These hairs are found on the thorax and on the first seven abdominal segments, just above and in front of a spiracle, or on a level with hairs on segments with spiracles. The spots may be in various forms: solid black extending to the base of the hair, or a black circle around a green base to the hair, or a solid black semicircle, or absent altogether. In the latter two cases, the hairs are smaller!
The caterpillar is an agricultural pest at times, attacking:
Indeed, tomato plants purchased from the local nursereyman have been the source of some of our specimens.
The caterpillars also attack garden plants such as:
The caterpillars grow to a length of about 4 cms.
The pupa develops inside a soft white silky cocoon. This is spun on the underside of a leaf and covered in bits of leaf and droppings. The adult emerges after a pupal duration of about three weeks in summer.
The adult moth is predominently brown in colour, with bunched hairs on its head which look like a short pair of horns. On each fore wing is a silvery figure of eight and a tiny silver 'S'. This silver 'S' distinguishes it from the related species: Chrysodeixis eriosoma, which is otherwise very similar. They both have a wingspan of about 3 cms. Some adults had grey patches adorning their fore wings. The hind wings are fawn in colour with a dark brown terminal area. Some of the chemical components of pheromones of this species have been elucidated.
The moth has an unusual natural posture. Unlike most moth species which seem to try to flatten themselves against the the surface on which they are resting, moths of this species seem to make themselves as narrow as possible.
The eggs are white and spherical. They are laid separately on leaves of a foodplant.
The species occurs over the whole of Australia, including Tasmania, and more rarely New Zealand and Norfolk Island. We have taken specimens in Melbourne, Sydney and in Bundaberg.
Further reading :
Ian F.B. Common, Moths of Australia, Melbourne University Press, 1990, pp. 43-44, 65, 459.
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