a name given by gardeners and others to a sort of small black flies found in vast numbers among fruit trees, in the spring season, and supposed to do great injury to them. Mr. Lewenhoeck preserved some of these flies for his microscopical observations. He found that they did not live longer than a day or two, but that the females during this time laid a great number of longish eggs. The gardeners who suppose that these flies wound the leaves of the trees, are mistaken: it is true that they feed on their juices; but they have no instruments wherewith they can extract these for themselves: they feed on such as are naturally extravasated; and when there is not a sufficient quantity of these for their purpose, they haunt the places to which the pucerons resort, and feed on the juices which these little creatures extravasate by means of the holes they bore in the leaves with their trunks.