The elephant in the garden

Although I've found elephant hawk-moth caterpillars on several occasions in the wild, I've only found it in our garden once. On that occasion the caterpillars were feeding on bogbean growing in our garden pond, but their usual food plant is rosebay willowherb.

The insect gets its name from its head and first two segments which are narrower than those behind and stretch out like an elephant's prehensile trunk. That changes dramatically if you threaten the caterpillar by giving it a prod, mimicking a bird's beak. Then those first segments are drawn in so that those behind swell ....

....... with this startling effect. The false eye spots on that third segment swell too, so that .....

.... the larva looks larger and far more menacing. Enough, apparently, to give it a reasonable chance of scaring away an inquisitive bird, but if that's not enough ......

... the caterpillar rears up like a snake and sways from side-to-side. All this enhances its survival prospects and increases its chances of living long enough to become .....

..... the very impressive adult moth.

Intimidation

If you're small, edible and confronted with a hungry carnivore your options are few. You can keep very still and hope you won't be noticed, run or take the bold option - stand your ground and try to intimidate your tormentor, which is exactly what this elephant hawk-moth Deilephila elpenor caterpillar did when I poked it with a grass stem. We found it in late afternoon (Deilephila means 'lover of evening') on the fellside near Blanchland in the Derwent valley, where it was climbing a rose-bay willowherb stem in preparation for another night's feeding.

The caterpillar was over three inches long, close to being fully fed. Notice the curved tail spike (not very menacing) and the four distinctive eye spots at the other end, which begin to become more menacing when the caterpillar realises it's under threat.

At that point it retracts its front three segments (that are longer and narrower than the others and have some resemblance to an elephant's trunk when it's feeding. This concertina-like contraction forces segments four and five, immediately behind and marked with the eye spots, to swell ............ and now those 'eyes' begin to look much more intimidating.....

.... especially when you look at it from this end, where you can compare its comparatively small real head with the false head formeed by swollen segment four.

Provoke it a little more and it will release its grip with the true legs at the front and, clinging on with pro-legs at the rear, wriggle violently like a snake. At this point its attacked will either be preparing to eat it anyway or will have been sufficiently intimidated to look elsewhere for a meal.

This is the commonest hawk-moth in the UK. You can find images of the adult insect at the excellent UK Moths web site.