11 



maining he expected to have reared numbers of the parasite, but in this he was mis- 

 taken, the gestation of the parasite apparently rendering the Hylaeus precocious, for 

 none of the bees that came out late produced any parasite : yet although the bees 

 which produced parasites have always been observed to assume the imago state before 

 others not parasitically affected, their appearance has varied according to the season, 

 from the middle of May to the middle of June. The parasitic pupae have almost 

 invariably shown themselves contemporaneously with the imago bee (never sooner), 

 whose contortions in wriggling itself out of the pupa-envelope may not impossibly 

 assist the parasite in driving the prominent dentate apex of the male pupa, or the 

 subcuspidate cephalothorax of the female, through the abdominal folds ; though it 

 may indeed also be assumed that this is accomplished, as Dr. Siebold seems to think, 

 by the larva. Among another lot of larva? and pupae of Hylaei, set apart and care- 

 fully watched, no symptom of Strepsipterous distension could be discovered in either 

 of those stages : however, he at length observed in two pupa?, on the right side only, 

 the dark markings usually preceding the development of the bee, and found, on the 

 pupa-pellicles being discarded the next day, Strepsipterous parasites ready to burst 

 forth had become conspicuously prominent on the opposite side. So long as the 

 Hylaei remained in the dark, the parasites made no attempt to leave their pupae, as 

 an incentive to which light appears essential ; for in one instance, some Hylaei having 

 become mature in a closed box, where they remained some time, none of the parasitic 

 skull-caps were removed ; so that it seems that unless aroused, after assuming the 

 imago state, by the stimulus of light, they die without emerging from the pupa-case. 

 Adverting to the observations of Mr. Westwood and Dr. Siebold on the hexapod 

 larvae of the Strepsiptera, and those of Mr. Newport on the whole series of changes 

 which take place in the ovum within the body of the female Stylops, herself contained 

 within that of the bee, he said that they did not affect the origin of these ova, nor did 

 it appear that their presence had been detected in any larviform Strepsipterous insect 

 obtained from a bee not taken at large, whereby the possibility of extraneous oviposi- 

 tion would be absolutely negatived : but the circumstantial evidence affecting the 

 relations of these hexapods with the Strepsiptera is so convincing, and the conditions 

 essential to their future maintenance and propagation — involved in the exploded 

 theory of their hyper-parasitic character — have been so nearly reduced to an argu- 

 mentum ad absurdum by Mr. Westwood, that no reasonable doubt can be entertained 

 upon this point. The male pupae, as Dr. Siebold affirms, always appearing towards 

 the commencement of summer, but never surviving the winter, it follows that the 

 hexapod larvae produced in the spring must, by a speedy transition, assume the pupa 

 state at the time when the first pupae of the males are observed ; which well accords 

 with the habits and equally rapid metamorphoses of the Polistes, while offering a re- 

 markable contrast to the tardy development of the larvae of other Strepsipterous 

 genera, which, like Stylops, Halictophagus, and these parasites on Hylaeus, are asso- 

 ciated with bees long retaining their immature condition, and enjoying comparatively 

 but a brief existence after quitting their cells in the imago state. It is therefore to 

 be regretted that Dr. Siebold, by collectively embodying under one categoiy results 

 derived from the Stylops and Xenos, and by simply setting forth the deductions so 

 obtained, should have afforded no opportunity of classifying the evidence for the pur- 

 pose of comparison ; whereby its bearing upon other points might be correctly ascer- 

 tained, and a consistent series of well-assorted facts more accurately propounded. 



