Having found or drilled a suitable cylindrical tube, they do nothing further to it but collect a sufficient store of provender for the nutriment of the young one, upon which they deposit the egg which is to produce it. The insect then flies away to collect a small quantity of clay intermingled with sand, and this they knead together by means of a viscous secretion which they disgorge, and this forms a concrete that hardens firmly and rapidly; to anticipate its rapid drying they speedily fly back, carrying this small ball within their mandibles, and with it they cover over the provision they have collected, and which, adhering to the sides of the cavity, forms a firm and hard division, effectually separating it from the next store of provision that is to be accumulated for the supply of the larva that will be hatched from the egg that is to be deposited, and the same process is repeated again and again until all the eggs are laid. In their development, which takes place near midsummer, the males precede the females by about ten days. They associate sometimes in colonies, often using the tubes of the straw thatch which covers cottages for their nidus. These bees are subject to the parasitical intrusion of _Fœnus jaculator_ and _assectator_, which I have repeatedly caught at Battersea, hovering opposite the cells of these insects bored in the shingles forming the enclosure of an old garden outhouse. These parasites are themselves peculiar creatures, forming a type distinct from the Ichneumons, and belonging to the group _Aulacus_, upon which see my paper in the ‘Entomologist,’ June, 1841. In these insects, the abdomen springs from immediately beneath the scutellum. _Chrysis cyanea_ and _ignita_ are also bred at the expense of these bees, neither of the species of which are uncommon; the smaller one, the _C. campanularum_, which is the smallest of our true bees, excepting perhaps one or two of the _Nomadæ_, I used to find in abundance upon the railings of the fields that skirt Hampstead Heath, on the right-hand going from London, parallel with the Vale of Health, and thence rising to the Holly enclosure of the Earl of Mansfield’s mansion. This spot has been productive to me of many very choice aculeate _Hymenoptera_, and supplied me with them in abundance at a time when even the chief metropolitan collections were bare of them. It has also furnished me with several very desirable _Diptera_ of extremely rare genera. The male of the larger species of this genus Linnæus called _florisomne_, from its habit of curling up its abdomen and antennæ, and passing the night in flowers. Those which they chiefly frequent are the species of Wallflower, and the _Campanula_, especially the round-leaved Throatwort. ------- Genus 22. HERIADES, _Spinola_. (Plate XIII. fig. 3 ♂♀.) APIS ** c 2 _γ_ partly, Kirby.