The life history of the black currant mite, Eriophyes ribis, Nal. is of a simple character from the month of May, when the buds of the current year's growth are entered, till March of the following year. During this time the mites live and multiply in the embryonic leaves producing the abnormal growth familiar to fruit growers as “big-bud.” From the end of March onward, however, the buds so attacked gradually die, and the mites which have lived in them for the past nine months are forced to find other plant food. At this time the buds of the black currant which the mites will eventually live in are rudimentary and it is the end of May before they are sufficiently developed for the acarids to enter.