350 NATURAL HISTORY OF ARTHROPODS. 



pairing has been often observed. The larva? are hatched in the body-cavity; the 

 Stylopida? are consequently viviparous. These hexapodous larva?, which are very 

 active and have eyes, escape by a dorsal opening from their mother, and, running 

 about on the female bees, are transported to the nest, where they quickly bore into 

 and bury themselves in bee-larva3. Once inside a bee-larva, the larva 

 of the fitylops moults in about a week, and appears as a footless grub 

 which feeds upon the fatty portions of the bee-larva. When the bee- 

 larva pupates, its parasite pupates within it. In becoming an imago, the 

 female Stylo2)s only bores out through the end of her own pupal skin, 

 FIG. 393. Xvnos and through one of the soft folds of the abdomen of the bee, protruding 



rossi, female. 



her head and thorax between two segments of her host, but never 

 leaving her pupal skin. The males leave the pupal skins, search out females, pair, and 

 die, usually in a few hours. Each female is supposed to bear about two thousand 

 young larva?, many of which, on account of their strange mode of life, die without 

 finding a suitable place for further development. 



There are but few genera and species of Stylopida?, among which the following 

 genera are perhaps best known, Xenos, with four-jointed antennae and four-jointed 

 tarsi; tit y lops, with six-jointed antenna? and four-jointed tarsi; and Halictophagus^ 

 with seven-jointed antenna? and three-jointed tarsi. 



Westwood has described a pupa, which he regards as belonging to the Stylopida? 

 and which was found in the abdomen of a hemipteron, under the name of Colacina 

 insidiator ; and the same author has also described a species, under the generic name 

 MyrmecolcvX) which is parasitic on ants in Ceylon. 



The RHIPIPHORID^E, a family containing only about a hundred described species, 

 includes insects, like so many other heteromerous Coleoptera, remarkable both for 

 abnormal adult structure and for parasitical earlier stages. The larva? of some are 

 parasitic on Hymenoptera, of others on Orthoptera. The beetles are all comparatively 

 small and generally wedge-shaped, the anterior portion of the prothorax and the 

 posterior portion of the abdomen usually diminishing gradually in size. The head is 

 vertical, and has large eyes ; the mouth-parts are well-developed, and the antenna? 

 have usually ten, in some females eleven joints, and are pectinate or flabellate in the 

 males, and often serrate in the females. The elytra are usually shorter than the 

 abdomen, often acutely pointed behind and dehiscent, sometimes very minute; a 

 few females resemble larva?, and want both wings and elytra. The beetles inhabit 

 flowers. 



Some discussion has arisen as to the actual food and mode of life of the larva? of 

 Rhipiphorida? in wasps' nests, but the following brief abstract of statements made by 

 Mr. A. Chapman in an account of the life history of Rhipiphorus (Metcecus) paradoxus, 

 a common European species which develops in the nests of Vespa germanica and 

 V. milgaris, are probably the facts of its mode of life. The female beetle probably 

 lays its eggs outside the wasps' nests ; the young larva, which has ocelli and is not 

 unlike the triungulin of the Meloida?, comes into the nest, possibly without help, and 

 enters the cell of a wasp-larva. Before the cell of the wasp-larva is closed up the 

 Rhipiphortis-\wrv& bores in between the second and third dorsal rings of the wasp-larva. 

 Later the TZA/prpAoms-larva, after feeding a while in the wasp-larva, breaks out through 

 the fourth ring of its host, moults immediately, and becomes a grub with poorly 

 developed legs. The parasitic larva now fastens itself firmly upon the fourth ring 

 of the wasp-larva, where it later moults again ; soon after this moult the parasite has 



