Bucculatrix cristatella

Wingspan about 7 mm. A tiny nondescript, grey-brown species not often seen as an adult. Usually recorded from the whitish ribbed pupal cocoon on Yarrow leaves. Adult: Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and describe the size and identifying characters. Cocoon on Yarrow: Unless identified by a recognised expert, a photo is required. If the photo doesn't show the key ID features then in the comments box describe the size and identifying characters you have observed. The adults fly in two generations; May and June, then July to August. The larva can be found in April and May and again in July. The larva feeds on Yarrow in a leaf mine to begin with, then later feeding externally on the leaves, shrivelling and blanching or browning them. Twice during its growth, it spins a white cocoonet in which it moults its skin. The cocoonet is constructed on the upper surface of a leaf, where it is easily detected. If held up to the light, the larva, or its cast skin retaining the larval shape, can be seen. Like other Bucculatriginae, the pupa, on the foodplant or adjacent plants, is in a distinctive whitish ribbed cocoon. In the Microlepidoptera Report 2011 it was classed as Nationally Scarce B and whilst it seems to be fairly widespread in England it is poorly recorded and is less common elsewhere in Britain.