The habits of Pompilids of the genus _Ceropales_ are analogous to those of the parasitic bees. Pérez has recently given us information as to a very curious form of parasitism in this genus; he says that when a _Pompilus_ has obtained a spider as provision for its young, it is pursued by a _Ceropales_, which lays an egg on the spider, thus as it were substituting in advance its own young for that of the _Pompilus_. Information as to the subsequent course of events in this case is not at present forthcoming. In another case a _Ceropales_ was observed to oviposit on the spider, not while this is being carried in, but subsequently by entering the nest for the purpose; a habit quite similar to that of some parasitic bees. Ferton has recently made the unexpected discovery that some _Pompilus_ act as robbers; one individual taking away by force the spider that another has captured and is carrying off. Lichtenstein described a Pompilid larva, that he afterwards ascertained to be _Calicurgus hyalinatus_, as possessing the extraordinary habit of feeding as an external parasite fixed to the dorsal surface of a spider; thus repeating, it would appear, the habits of some of the Ichnemonidae, though the perfect Insect (Fig. 143) does not differ in structure from its congeners. Emery has given an account of some Pompilids that do not bury their prey, but after stinging it and depositing an egg, simply leave the spider on the spot. {107}Buller has described the habits of a Pompilid in New Zealand; his account is interesting because it shows a remarkable similarity in the proceedings of this antipodean wasp to those of its congeners on our own side of the world. The species is not scientifically named, but it appears that it is known in New Zealand as "the Mason-bee." It forms a nest of yellow clay consisting apparently of about eight cells, each of which is filled with one or more spiders in a paralysed condition. The figure given of the larva of this Insect by Buller shows it to possess a peculiarly formed head. It is pleasing to find that Pompilidae do not make use of cruel methods when others will serve their purpose. We are informed that a large Australian Pompilid—_Priocnemis bicolor_—may find a _Cicada_ sucking sap from a hole it has pierced in a tree. The _Priocnemis_ has not the art of making the puncture necessary to procure sap, so the wasp seizes the _Cicada_, and shakes it till it leaves its hold and flies away, when the _Priocnemis_ takes its place and sips the sap. It is added that the wasp never hurts the Cicada. FAM. 3. SPHEGIDAE. _Pronotum free from the tegulae; when the stigmatic lobes extend as far back as the wing-insertion, they are placed below it and separated by a space from it._