2810 Entomological Society. 



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- 

 menturn 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 pups 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 category 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. 

 With regard to the genus to which these parasites upon the Hylaei may belong, the 

 general conformation of the antennae and tarsi might tend to associate them with 

 Xenos, yet their habits, consorting with the Mellifera, bring them into close relation 

 with Stylops and Halictophagus, so that they seem to supply a connecting link be- 

 tween Xenos and Stylops, coinciding with the position which the Hylaei themselves 

 occupy between the Vespidae and the Mellifera, thus constituting a new genus, for 

 which he would propose the name of Hylecthrus, readily distinguished at first sight 

 by the broad laminae of the antennae, which are nearly of equal width throughout, 

 whereas in Xenos they gradually taper from the middle to the apex ; the palpi in the 

 former being less conspicuous, and the thorax less, considerably more gibbous, as well 

 as wider and shorter in proportion. With regard to an opinion which has long pre- 

 vailed, that the larvae of the Hylaei are parasitical feeders upon the stores of other 

 Mellifera, it does not appear to be borne out in those which he has reared ; for having 

 obtained many specimens from cells adapted to the size of the larvae, and constructed 

 in appropriate channels through the pith, the peculiar transparent tapestry of the 

 Hylaei being continued throughout each series of cells in uninterrupted succession, he 

 could not but infer that these are no casual intruders or predatory usurpers, but lineal 

 descendants of the original constructors and purveyors. On more than one occasion 

 he had reared Hylaei from briars wherein a species of Osmia was also met with, but 

 the cells of the one were perfectly distinct from those of the other ; the Hylaeus having 

 simply availed itself of an excavated briar after the Osmia had completed its labours, 

 a deposit of acidulous honey being found intermediate between the two sets of cells. 

 Whence could this honey have proceeded, and for what purpose could it have been 

 collected ? Can this be the nature of the food upon which the Hylaeus larvae subsist, 

 and could it have found its way hither by exuding from the cells of the Osmia ? This 

 is a problem involving many points difficult to explain, the solution of which — as de- 

 fining the habits and economy of the Hylaei — offers an interesting subject of inquiry. 

 On one occasion he found some pupae of Hylaeus in a mud-cased briar containing the 

 deserted cells of an Odynerus, the Hylaei in this instance being arranged obliquely : 

 it will, however, scarcely be contended that the Hylaei were parasitical feeders upon 



