Elephant hawk-moth: caterpillar, lifecycle and is it poisonous?

If you’ve been lucky enough to encounter a hawk-moth, you’ll know you’ve seen something special. They’re big. They’re juicy. They’re beautiful. As a native of Birmingham might put it, they’re proper bobowlers. 

The UK has several native species of hawk-moth, but the elephant hawk-moth (Deilephila elpenor) is one of our most common and widespread, found in gardens, woodland edges and open countryside. It’s a great beginner’s moth for the budding lepidopterist – it comes readily to light traps and is pretty recognisable!

Caterpillars

The caterpillars, or larvae, can grow to the length and thickness of a large thumb. They are usually dark brown and trunk-like, hence their name, but bright green forms are not uncommon. Look for their large eye spots and spiked tail.

When they’ve had their fill of leaves and grown to full size, their next task is to look for a safe place to pupate (turn into a moth). To do this, they need to come down from their leafy larders and search for leaf litter to hide in.

This is when they become most noticeable. They’re often encountered by gardeners in late summer while sunbathing or ambling about. They can put on quite a turn of speed, undulating across paths, lawns and bare ground. When they’ve found the right spot, they’ll bury themselves beneath dry leaves and develop a hard casing, or chrysalis, in which they’ll undergo the near-magical transformation over winter from caterpillar to moth. 

Adults

The adult moths emerge at night between May and July.  They can be up to 6cm across from wing tip to wing tip and are bright pink and olive green. They feed on the nectar of night-scented flowers such as honeysuckle and lay their eggs on rosebay willowherb, bedstraws and fuschias.

Like all hawk-moths, they’re strong fliers. Their ability to beat their wings quickly and hover into position when feeding has earned them the ‘hawk’ part of their name.

The closely related small elephant hawk-moth (Deilephila porcellus) is similar, but as the name suggests it is smaller than its more common relative and tends to be a brighter pink. If in doubt, look for the pink stripe down the body of the larger species which the small elephant hawk-moth doesn’t have.

Are elephant hawk-moths poisonous?

Despite their bright and colourful appearance, elephant hawk-moths (both as adults and caterpillars) are not poisonous and are harmless to both people and pets.

In fact, the large caterpillars only pretend to be fierce. When threatened by a hungry bird (or unsuspecting passer-by) they retract their heads and puff out their bulbous necks. Complete with fake eyes, this display is sometimes enough to convince their attacker that they are dangerous and snake-like (and has perhaps earned them their fearsome yet unwarranted reputation).

So why are they pink?

Rather than acting as a warning to would-be predators, the moths’ bright colours advertise their presence to amorous suitors. Their night vision is particularly good, allowing them to meet up with other hawk-moths – and locate and feed from nectar-rich flowers – all in solid darkness.

And after a busy night of feeding, moths can rest during the day among their caterpillars’ favourite food plants without fear of standing out – happily they blend in nicely with the bright pink flowers of willowherbs and fuschias.