A caterpillar mystery has been solved! At the beginning of July, volunteer Neville discovered a mysterious caterpillar crossing the busway track. Unable to identify it, he contacted the Royal Entomological Society who identified the caterpillar as an emperor moth caterpillar, Saturnia pavonia.
The the UK's only native silk moth, it is widespread, although not especially common. The moths are very large - the females have a wingspan of up to 10cm. During the day, females rest in low vegetation, releasing pheromones to attract males. The males, which are active during the day, pick this scent up with their large, feathery antennae. Apparently, male emperor moth can detect a female from up to 7 miles away!
Caterpillars go through different stages, known as instars, as they grow. As the caterpillars grow, they replace their skin and shed their old one. After the first moulting process, the caterpillar is referred to as a second instar. After each subsequent moult they are known as third, fourth and fifth instars. The caterpillar spotted by Neville was a second instar caterpillar. The caterpillars vary in morphology between moults and there can even be variation within stages - making them difficult to identify!
Male emperor moth Female emperor moth