We have but one species of the genus, although the southern parts of the Continent abound in them. The habits of ours differ very considerably from those of the preceding genus. First, in the peculiarity just described, and then in the formation of their nests. They do not, like the majority of the wild bees, excavate or bore a cavity for themselves, but take one already formed by the xylophagous larva of some considerable insect, such as _Cerambyx moschatus_, or _Cossus ligniperda_. This they line, to the depth suitable to them, with cottony down which they scrape from the leaves or stalk of the Woolly Hedge-nettle (_Stachys Germanica_), the Wild Lychnis (_Agrostemma_), and other woolly-leaved plants. In collecting this wool the insect is very active, scraping it off rapidly with its broad mandibles, and as this is doing she gradually rolls it up into a little ball, making with the vibration of her wings a considerable hum all the time she is gathering it, and when the ball is sufficiently large she flies off with it to her nidus; this operation she continues until sufficient is accumulated for her purpose, which consists in lining the cavity with the material; she then forms cells within it in succession, gluing the same material together to resist the escape of the mixed store of pollen and honey she intends to fill it with, having in the operation smoothed the sides of the cell which is closed after the deposit of the egg, and another similar cell is then proceeded with, and this is repeated until the selected cavity is filled, or that she has exhausted her store. Having completed her labours, she wanders away. Sometimes the cavity is large and admits of the conjunction of many of these cells together; in that case they are all collectively covered with the same envelope of downy substance. The larva, having consumed its entire store of food, spins a cocoon of brown silk wherein it remains throughout the winter, and with the evolution of spring, feeling its propulsive energy, it changes into the pupa. In June and July, but earlier if the weather be continuously warm, the imago comes forth in its maturity, to live its little life of labour intermingled with pleasure, and in its pleasing hum to give cheerful notification of its perfect satisfaction. ------- Genus 21. CHELOSTOMA, _Latreille_. (Plate XIII. fig. 2, ♂♀.) APIS ** _c_ 2 _γ_ partly, Kirby.