As I walked into town, the crunch of beech mast underfoot made me glance down. My eyes were immediately drawn to a plump, green hawkmoth caterpillar undulating across the pavement. It’s common for the mature larvae to leave their natal food plants and go wandering in search of a place to pupate in loose soil beneath their host tree, but this individual was perilously close to the edge of the kerb and, with a steady stream of oncoming traffic, I didn’t fancy its chances if it attempted to cross.
Crouching down, I gently coaxed it on to my finger, looking around for somewhere safe to relocate it. Unfortunately, it was a barren stretch of road, the bordering gardens enclosed by tall brick walls.
At first sight, I suspected it was an eyed hawkmoth larva, which feeds on sallow, willow and apple. Since I have a number of crab and culinary apple trees in my garden, I decided to turn back and release it there. As I waited to cross the road, passing motorists glanced quizzically at my cupped hands. It was only a five-minute walk, but the caterpillar was very active, pirouetting around and rearing up in a defensive posture, its head weaving from side to side. As it inched its way across my palm it gripped my skin, the tiny barbs on its feet attaching like Velcro.
Arriving home, I was able to examine the creature more closely and began to question my initial identification. It was an impressive specimen, its body the length of my thumb. Like most species of hawkmoth caterpillar, it sported a stubby tail horn. This individual’s was curved like a rose thorn and turquoise blue, characteristic of both eyed hawkmoth and lime hawkmoth larvae. Both species have pale oblique stripes along their sides and can develop small red subdorsal markings but, as I was informed after posting photos on a natural history forum, the warty yellow tubercles on its anal flap were a distinguishing feature of the lime.
Commonly found in parks and gardens, lime hawkmoth larvae feed on a variety of deciduous trees, so I was able to encourage the wanderer on to the foliage of my silver birch.
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