Behaviour
This adult individual of Eumorpha labruscae from the Natural History Museum collection shows how the blue-green coloration of the live moth fades to yellow-green after death. © Alessandro Giusti
When searching for a mate, the adult male flies up wind using its antennae to pick up the pheromone emitted by the female.
As a deterrent against predators, the 5th instar larva retracts its head and the first two thoracic segments into the body and the swollen third thoracic segment with the eye-spots takes the shape of a snake head. At the same time the caudal patch throbs like a pulsating organ. (See video)
This is not the only caterpillar that imitates a snake as a deterrent against predators. Many other species of hawkmoths have caterpillars that can resort to this kind of disguise when disturbed (Hemeroplanes, Erinnyis, Daphnis and others) and the caterpillar of the spicebush swallowtails (Papilio troilus), of the eastern United States, is also a very good snake mimic.
The adults of this moth can emit a loud squeak when agitated and readily use their tibial spines when carelessly handled.