As a gardener, I love butterflies but detest caterpillars. Whenever I see them on my plants, I flick them off and that is the last I see of them. This is an account of a caterpillar that I flicked off three times and each time, it found its way back to the host plant.
It was a large caterpillar about 7 cm long, black in colour, with a pattern of gold ringed ‘eyes’ and white transverse bands made up of small closely spaced white spots). At the tail end, sticking up, was a spur. This was identified by an entomologist as the caterpillar of a hawkmoth.
I found two of these caterpillars feeding on a plant of Impatiens walleriana (busy lizzie) growing in mixture with other flowering plants on a raised flower bed in my garden. The bed is one brick high and is demarcated by a line of bricks. I flicked the caterpillars off with a stick and they landed about 30 cm away on the lawn . On the next day, one of them was back on the plant. The other was not seen again. At first I thought this was a caterpillar that I might have overlooked. I flicked this off and made sure there were no other caterpillars on the plant. An hour later, I noticed it was back on the plant.
Intriqued, I flicked it off for the third time and this time I watched as it recovered from the shock and crawled on the grass in the direction of the host plant. When it arrived at the dividing brick wall. It tried to climb the wall but gave up. Instead it crawled on the grass alongside the brick away from the host plant until it came to a gap between two bricks that was filled with soil and small weeds. It crawled up this gap to the top of the bed and headed straight for the host plant, past a number of other plants of other species. I was surprised by its ability to make a detour and still find its target.
I was going to give the caterpillar a rest before putting it though some further tests, but when I came back a few hours later, it had disappeared.
Can anyone put me in touch with other accounts of homing ability in caterpillars?