Now is a good time to search for the two Coleophora species that feed on heather. Coleophora pyrrhulipennella cases are black and made of silk, whereas those of C. juncicolella are made from fragments of heather and are incredibly cryptic.
Both species are best found by sweeping heather. The pyrrhulipennella case is sufficiently obvious that it can be found by searching through the swept detritus.
However, the cases of juncicolella are so difficult to find that the best technique is to place your sweepings in a container overnight and you'll then find that the larvae have climbed up the sides.
It may or may not be of note that I swept lots of cases from an ungrazed heath two days ago but none at all with a similar amount of effort on a grazed heath today.