Double-striped Knot-horn Cryptoblabes bistriga
The Double-striped Knot-horn is a very variable species. Usually the middle part of the wing is darker than the outer two parts, often with red elements. But in some animals all three parts are about the same colour: dull grey or buff for instance. Sometimes all dull animals appear even without the white stripes. In the picture a very dull specimen indeed. The wingspan is 17 to 21 mm. The adults fly by night only, but are attracted to light.
The caterpillar is always brownish with dark markings on the first few segments. It usually lives between leaves which it spins together. The food plants are oak and alder, but it is suggested it also feeds on shrubs and birch. The larva overwinters undeep underground.
The Double-striped Knot-horn is double-brooded. Adults are on the wing from the end of April to September. The first brood is much smaller than the second. In between is a period in June when numbers are very low. It is a local species of woodlands and heath, which means it is common in certain places, but scarce elsewhere. This is true not only of Britain, but of Europe as a whole.