A striking caterpillar recently stopped us in our tracks on the Downs. With its glossy burgundy back, burnt-orange sides and considerable size, looked unlike anything I regularly encounter around the distillery.
This is the caterpillar of the Goat Moth, Cossus cossus, one of Britain’s largest and most unusual moths.
The Goat Moth is considered nationally scarce in Britain. It has declined substantially and now survives in scattered locations, principally across southern England. The loss of veteran trees, old orchards and undisturbed woodland habitat has reduced the places in which it can complete its extraordinary life cycle. Its presence on the Downs is therefore a significant and encouraging wildlife record.
The caterpillar can grow to around 10cms in length and spends most of its life hidden inside the trunks of living broad leaved trees, feeding on wood rather than leaves. Willow, poplar, oak, ash, birch, alder and old fruit trees can all provide suitable habitat.
Wood offers little nutritional value and takes a long time to digest. As a result, the caterpillar may remain inside its host tree for three to five years, overwintering several times before it reaches maturity. It eventually leaves the tree to find a suitable place to pupate. This brief journey provides one of the few opportunities to see it in the open.
Its unusual name comes from the strong, goat-like smell produced by the caterpillar. Signs of its presence can include holes low down on a tree trunk, coarse wood fragments and dark sap seeping from the bark. The fermenting sap can attract other insects, turning a single occupied tree into a valuable miniature habitat.
The adult Goat Moth is equally impressive. Its heavy body and intricately patterned grey-brown wings resemble tree bark, providing excellent camouflage. With a wingspan that can approach 10cms, makes it among Britain’s largest and heaviest moths.
Finding one on the Downs reinforces the importance of retaining mature trees, deadwood, old orchards and untidy corners. These habitats can look unremarkable, yet they support species that require years of stability to complete their life cycles.
A rare and remarkable creature, quietly living within the landscape for years before revealing itself.
