The name Gypsy Moth is associated with several different iconic things. To some it will be a bi-plane built by De Havilland in the 1930's, to far more it will bring memories of Sir Francis Chichester's voyage in Gipsy (note spelling) Moth IV which broke the record for solo navigation round the world, and many other records on the way. Sir Francis was a pioneering aviator and was the first to fly the Tasman Sea from east to west, in a Gypsy Moth of course.
Lymantria dispar, that I found in my moth trap was quite different, but it was the first I've seen. A moth associated in this country with the fens of East Anglia it declined with the drainage of its habitat and became extinct by 1907. It is still common on continental Europe where it becomes a pest species. Occasionally wandering males find themselves on this side of the Channel, but with no females they can't breed and offer no threat. When the population is high, the caterpillars devastate timber plantations and ornamental trees. The same is true in North America where it was accidentally introduced in 1868 when some caterpillars escaped from a laboratory.
The male, above is brown and has a pair of complex antennae. The female, is mainly white and simple antennae, is slightly larger with a wing span of up to 6cm, but despite the wings it is flightless. When she emerges from her cocoon she releases a pheromone that attracts the male (this is where the antennae are used) and having mated she lays her eggs on the tree. Neither male of female feed and both die soon after mating.
The closest relative of the Gypsy moth that breeds in the UK is the Black Arches, Lymantria monacha. I caught the male above a couple of days ago. The female Gypsy moth bears a resemblance to this but is slightly larger, with a blunter body and fewer dark markings. Black Arches is an Oak feeder, but as far as I know doesn't reach pest proportions.