Adult moths are small with a wingspan only reaching 1.5cm. Their wings are mainly white, however, have variable light-brown markings. The markings generally comprise 2 thick brown bands that cross the white wing-scales. There is also lots of irregular brown dotting.
Larvae appear like small black caterpillars (1.5cm) which overwinter as young larvae. However, these begin leaf miners so are difficult to detect at this stage. Once fully grown, larvae break from leaf mines and spin dense webbing that can span a whole branch of a tree. Within the communally spun webs, they continue to feed on foliage until they pupate, spinning silk cocoons.
There are other species of moth that spin similar webs to the hawthorn moth, however, these do not infest cotoneaster. If you have webs of similar description in your garden, you may want to take a look at our records for the box tree moth, browntail moth and the ermine moths.