Hunting for suitable egg laying sites

Dainty Swallowtail

The Dainty or Dingy Swallowtail – Papilio anactus – is the most common and numerous swallowtail in this area. Anyone from Wagga to Albury and probably beyond who grow any citrus will find this butterfly and it’s caterpillars in their trees. The caterpillars can become so numerous they can totally strip a small citrus of all it’s leaves.

The Dainty or Dingy Swallowtail
The Dainty or Dingy Swallowtail
Hunting for suitable egg laying sites
Hunting for suitable egg laying sites
Always ready to fly away at the first sign of danger
Always ready to fly away at the first sign of danger

The butterfly is quite striking, with it’s black and white markings and red and blue spots on the margin of both hind wings. It is a very restless flyer when feeding and searching for egg laying sites, and is constantly flitting from one spot to the next.

Dainty Swallowtail egg on new grapefruit growth.
Dainty Swallowtail egg on new grapefruit growth.

The eggs are laid on the fresh new growth of citrus – small, single lemon-yellow and round. The eggs hatch into ravenous black and orange caterpillars. The markings change as the caterpillar matures. When disturbed, they can arch up and extend a flexible, orange coloured forked gland called an osmeterium which can squirt a fluid with a mildly offensive odour of rotting citrus.

Young Dainty Swallowtail caterpillar.
Young Dainty Swallowtail caterpillar.
A disturbed caterpillar displaying it's osmeterium.
Disturbed caterpillar showing osmeterium.
Mature caterpillars on a lemon tree.
Mature caterpillars on a lemon tree.

 

Although the caterpillars are quite conspicuous, their chrysalis stage is so well camouflaged they are easy to miss. The caterpillars pupate in the trees upon which they have fed, matching the colour and markings on the chrysalis to blend in to the anchoring branch. I have seen them in various shades from green to brown and an exact match to the surrounding citrus branches.

Dainty Swallowtail chrysalis on a Hand of Budda citrus.
Dainty Swallowtail chrysalis on a Hand of Buddha citrus.
Same chrysalis fro a different angle, blending in.
Same chrysalis from a different angle, blending in.
Chrysalis from above - note the silk anchor threads.
Chrysalis from above - note the silk anchor threads.

 

More information on the Dainty or Dingy Swallowtail can be found at http://lepidoptera.butterflyhouse.com.au/papi/anactus.html