IV. 



Facts and Theories in the Development 

 of Insects. 



REFERENCE was made in Natural Science for March 

 (PP- 55) 56) to the Stylopidse. These insects were formerly 

 regarded as a special order (Strepsiptera), but most entomologists 

 now consider them to be a very aberrant group of Beetles (Coleoptera) 

 related to the Oil Beetles (Cantharidse) and the Rhipiphoridae. In 

 both these families the larvae live parasitically on the grubs of bees 

 and wasps. In the Stylopidse we see the parasitic habit continued 

 in the female imago, and such modifications in the male that its 

 coleopterous affinities are much obscured. Moreover, the host is not 

 prevented from attaining its imaginal state ; indeed, it must be 

 allowed to do so to secure the fertilisation of the parasitic female 

 Stylops by her free-flying mate. 



Although many species of Cantharidae and Rhipiphoridae are 

 known, the life-history of few only has been worked out. The 

 classical researches of Newport and Fabre long ago made known 

 the " hypermetamorphosis " of M^/o^' and Cantharis, -which, belong to 

 the former family. In 1870, Dr. Chapman and Mr. Murray (i) 

 discovered the transformations of Rhipiphovus paradoxus, the larva of 

 which they proved to be first a minute active hexapod, then an 

 internal and then an external parasite on the grubs of the social 

 wasps (Vespidae). And now Dr. A. Chobaut (2) has worked out 

 most of the life-history of another beetle of the same family, Emenadia 

 fiabellata, belonging to a genus unknown in Britain, and with very 

 few European species. He has shown the great similarity of its 

 transformations to those of R. paradoxus, and finds that its hosts are 

 the grubs of a species of solitary wasp {Odynerus). 



Three Odynerus grubs were found within the cavity of a reed, 

 each in its cell closed by earthen walls, as is the habit of the wasp 

 in making its nest. The grubs did not pupate in May, the usual 

 season ; but early in June a parasitic larva emerged from each, and 

 fed incessantly for twelve days, sucking at the ventral region of its 

 host until only the skin and mandibles of the latter were left. This 

 parasitic larva is described as entirely without legs, eyes, or antennae, 

 and with a suctorial mouth. 



