The two species of elephant hawk-moth are - Deilephila elpenor (large) and Deilephila porcellus (small)
The elephant hawk-moth is a beautiful lime/olive green and pink moth with a plump, furry body. There are 2 species, the larger, Deilephila elpenor with a wingspan of 55-65mm, and the smaller, Deilephila porcellus has a wingspan of 45-50mm.
The moth is a night flying species, found in all parts of the UK and much of Europe. They favour waste ground particularly where there is an adundance of willowherb and bedstraw species (hmm - sounds like my garden!). The adults feed on the nectar of honeysuckle and valerian and lay their eggs on willowherb.
The 'elephant' part of their name is derived from the appearance of the caterpillars which are said to resemble elephant's trunks.They are fat, wrinkled, leathery and greyish-brown in colour. The segmented caterpillars taper towards the head end and has 2 prominant eye spots on the 4th and 5th segments. When disturbed the caterpillar contracts its head inside its body so that the eyespots now appear at to be on the head and the caterpillar resembles a small snake - somewhat frightening to potential predators. The caterpillars remain mostly hidden at the base of their food source during the day, only coming up to consume enormous quantities of the plant during the evening and night.
When the caterpillars are ready to pupate, they bury themselves in the soil and form a chrysalis of silk, earth and leaf fragments. This pupa is around 40 mm long and remains buried in the soil, hibernating and transforming into the adult form before hatching in the early summer.
http://www.bbc.co.uk
http://www.bioimages.org.uk/HTML/T13736.HTM