naughty but nice

The bee hawk moth feasts on gardenias using different guises, says MARTYN ROBINSON

If you notice that some of the glossy new leaves on your gardenia are missing, or appear to have been chewed, have a look for large caterpillar droppings, almost the size of peas, on the ground underneath the foliage. You will usually find the rather attractive, often surprisingly large, boldly coloured culprit on the plant, directly above the freshest droppings. This is the caterpillar of the bee hawk moth (Cephonodes kingii), or gardenia bee hawk.

This species is one of the more tropical native insects that used to be a rare summer visitor to New South Wales but is now a resident, as climate change has shifted the temperature in its favour. It appears to be moving further south across the country. While it mostly feeds on species in the family Rubiaceae, to which gardenias belong, you’ll also find it tucking into a number of native plants.

The caterpillar comes in two forms: a black, grey and white one that really stands out; and a camouflaged green and white striped one with a grey back (above). Both have an orange head, and little red circles on their sides. They also both have a dangerous-looking but totally harmless spike on their tail end.

No-one knows why there are two colour forms. They probably taste nasty, so the pattern on the more visible one could be a warning, and the camouflaged one might do better at avoiding parasites that lay eggs in these caterpillars.

The adult moths are spectacular. Their bodies are velvety green and yellow, with see-through wings like their namesake, the bee. Also like the bee, they visit flowers during the day, hovering like hummingbirds as they sip nectar. Apparently, they are good pollinators of pawpaw, too.

So are they a problem in the garden? Well, yes, as they do eat the leaves and buds of gardenias. But I think they more than make up for the loss with their impressive caterpillars and fascinating moths.

Martyn gardens mainly on Sydney’s Northern Beaches