Newly laid egg
Fertile egg, two days old, that has acquired the purplish-brown apical ring
Egg, three days old showing the apical depression starting to form
Egg, four days old on leaf of Robinia foodplant
Egg showing the developing mandibles (mouth parts) of the larva inside the egg
Egg, six days old, and eight hours before hatching. The mandibles of the larva are on the right hand side.
Egg, six days old, and two hours before hatching.
The mandibles of the larva are now at the top of the egg as it slowly eats open the egg.
A small opening has already been formed by the 'egg tooth', seen in the middle of the reflective white patch near the top of the egg.
First instar larva emerging from egg
First instar immediately after emerging from egg and after making a silk pad (Photo 1).
Head horns and tail fork have not started to expand and are pink coloured.
Closeup of egg near larval emergence showing the unexpanded horns of larva on left hand side
Closeup of newly emergent larva from its egg with its unexpanded horns
2 minutes after Photo 1, larva starting to expand horns and tail fork, and starting to eat empty egg shell
3 minutes after Photo 1, tail fork finished expanding
5 minutes after Photo 1
10 minutes after Photo 1
15 minutes after Photo 1, head horns fully expanded
30 minutes after Photo 1, head horns and tail fork now starting to harden and darken
45 minutes after Photo 1, closeup of darkening horns and tail fork
80 minutes after Photo 1, darkening nearly complete
Sixteen hours after Photo 1, the larva is fully coloured and has had its first meal of green leaf. It is sitting in a disturbed pose with its front end raised.
First instar larva aligned along midrib of Robinia leaf. Silk pad on which it rests is obvious, and also the silk trails to where it has been eating at holes in edges of leaf.
Late first instar larvae that have acquired green colour from eating green leaves of the foodplant
Closeup of head of first instar larva.
Long white bristles below the mouth are used to detect the silk trails
Second instar larva after moulting, with its previous head capsule still present
Intermediate instars resting on their silk pads
A fourth instar larva in a disturbed pose
Head of fourth instar, 45 minutes before moulting. Head of new fifth instar, still within the body-skin of the fourth instar can be clearly seen behind the (now empty) head capsule of the fourth instar.
Head of fifth instar, 15 minutes after moulting and after expanding its head horns. Old fourth instar head capsule is still attached.
Early fifth instar larva side view, resting on its silk pad in a disturbed pose with its front and rear ends elevated
Fifth instar larva, dorsal view
Fifth instar larva, showing an abnormal number of yellow lunettes
Head of fifth instar larva
All photography by R. Grund unless stated otherwise.