Caterpillars munch on:
Adults take nectar from tubular flowers such as:
In September, caterpillars leave the food plant and wander around, looking find a place to pupate. Once they’ve found a suitable spot, they nestle amongst fallen leaves or just below the surface of the soil. They then transform into a chrysalis and stay like that until emerging as adult moths the following May.
There is even more about this species on the main Butterfly Conservation website
The large, brown caterpillars of the Elephant Hawk-moth are said to resemble an elephants trunk and have conspicuous eye-spots on their back. When threatened by a predator, these caterpillars tuck their head back towards their body and puff themselves up, giving the impression of a wide-eyed snake.