The wood white butterfly, which is found in Europe and Asia, can be recognized by its slow, fluttering flight.
Male and females have a black tip on each forewing - this is darker in males than in females.
Female wood whites in Great Britain lay their eggs on vetches and bird's-foot trefoil.
Caterpillars are green and easily blend in with their food plants.
The caterpillars fors their chrysalises on these plants and the hibernate there.
This means that the wood white may remain as a chrysalis for up to ten months of the year.
In some years, there are two generations of butterflies. The normal brood emerges in May or June and an additional one emerges in July or August.