checking water mint for associated species this lunch time i came across this case on the flower head of water mint (Mentha aquatica). it is the case of a case-bearing moth Thiotricha subocellea. this species has been seen on the UEA campus only in 2015 as one adult and now three larval cases. The larvae are inside of the case and feed by emerging slightly from the case and eating the host plant. they will pupate and overwinter before emerging as adults in summer 2016. They are listed as nationally scarce category B.
Thiotricha subocellea at UEA
Thiotricha subocellea - (Stephens, 1834) - Wingspan c. 10mm. This species has a scattered distribution across England and Wales, into parts of Scotland, and flies during July and August. The larva feeds on wild marjoram (Origanum vulgare), occasionally on other herbs, feeding in autumn on the seeds from inside a case constructed from the calyxes of the foodplant. As it grows, the larva attaches further calyxes, resulting in a rather distinctive appearance. The adult moths are small and whitish, marked with grey and black.