_Crabro leucostomus_ has been observed by Fletcher to form cells for its larvae in the soft wood of broken willows: the food stored therein consists of two-winged flies of the family Dolichopodidae. This _Crabro_ is parasitised by an Ichneumonid of the genus _Tryphon_, and by a two-winged fly of uncertain genus, but belonging to the family Tachinidae. The metamorphoses of _Crabro chrysostomus_ have been briefly described by Verhoeff: the food stored consists of Diptera, usually of the family {130}Syrphidae; the larva spins an orange-red cocoon, passes the winter therein, and assumes the pupal form in the spring; there is, he says, a segment more in the female pupa than there is in the male. The species of the sub-genus _Crossocerus_ provision their nests with Aphididae, but _C. wesmaeli_ makes use, for the purpose, according to Ferton, of an elegant little fly of the family Tipulidae; according to Pissot this same wasp also makes use of a species of _Typhlocyba_, a genus of the Homopterous division of Rhynchota. Supposing there to be no mistake as to this latter observation, the choice of Diptera and of Homoptera by the same species indicates a very peculiar habit. _Fertonius_ (_Crossocerus_) _luteicollis_ in Algeria forms cells at a slight depth in sandy soil, and provisions them with ants. The ant selected is _Tapinoma erraticum_, and the individuals captured are the wingless workers. The mode of hunting has been described by Ferton; the wasp hovers over one of the ant-paths at a distance of a few millimetres only above the surface, and when an ant that is considered suitable passes, the _Fertonius_ pounces on it, stings it, and carries it off to the burrow; forty or fifty ants are accumulated in a cell, the egg is laid in the heap of victims about one-third of the depth from the bottom; the resulting larva sucks the ants one by one, by attaching itself to the thorax behind the first pair of legs. There is a very interesting point in connection with the habits of this species, viz. that the ants are not only alive, but lively; they have, however, lost the power of co-ordinating the movements of the limbs, and are thus unable to direct any attack against the feeble larva. Ferton thinks there are three generations of this species in a single year. * * * * *