OF CERTAIN CHALCIDIDjE AND ICHNEUMONIDjE. 65 



having " singularly distorted antennse, and the wings almost rudimental," thus offering, 

 he says, " a strikingly opposite analogy to other hee-parasites." But without describing 

 M. Audouin's insect, either generically or specifically, or explaining in what its " stri- 

 kingly opposite analogy" consists, this naturalist has proposed to designate that insect 

 Melittobia Audouinii. A name thus given without a description, either generic or spe- 

 cific, cannot, however, be adopted ; even if that insect should ultimately prove to be iden- 

 tical with mine. The necessity for precise description when a name is imposed will at 

 once be perceived, in the fact that both Reaumur and DeGeer long ago found Chalcidi- 

 dous parasites in the nests of mason-bees, and yet, up to the present time, their species 

 have not been clearly made out. Reaumur * found more than thirty larvae of one species, 

 and in other nests ten or twelve of a larger species. DeGeer f also found twenty speci- 

 mens of another kind in a single cell, and which he reared to the perfect state. He re- 

 marks, too, that the larvae of mason-bees are very subject to be destroyed in their cells by 

 the larvae of different species of Ichneumon. The species found by DeGeer seems to have 

 been a Pteromalus, or nearly allied to that genus. These facts are interesting, as showing 

 that mason-bees are infested by many parasites. The occurrence of Audouin's insect in 

 the nest of Odynerus, as well as of Osmia and Anthophora, as stated, renders its identifica- 

 tion with the insect I have discovered very doubtful. I have never found my species in 

 any other than the nests of Anthophora. 



The habits of this insect may be inferred from the peculiar organization of the male. 

 From both sexes being found in the closed cells of the bee, and from the absence of a long 

 ovipositor in the female, we may conclude that the eggs are deposited while the nest is 

 being provisioned, or immediately before it is closed ; and that, like the true Ichneumons, 

 the parent either plunges her eggs into the body of the newly-hatched bee-larva, or 

 attaches them to its skin. The bee-larva, like many other species similarly circum- 

 stanced, continues to feed, and grow, and supply nourishment to the parasites ; and by 

 the time it has consumed the whole of its provision, these also are far advanced in growth. 

 When the young bee is entirely destroyed these are matured, and prepare for their change 

 to the state of nymph, which they assume lying loosely in the cell, without spinning sepa- 

 rate cocoons. 



Erom the circumstance that although both sexes are found moving about freely in the 

 cell, the male is by far the least active, and especially from the fact that his organs of 

 vision are merely single ocelli, instead of large compound eyes, as in the other sex, I am 

 led to the conclusion that impregnation is effected before the insects quit their habitation ; 

 because ocelli, being different in their structure from the individual parts of the com- 

 pound eyes, are fitted only for near vision. The difference of structure consists in this : 

 the cornea, or external surface of each part of the compound eye, which is individually as 

 perfect, as an organ of vision, as the ocellus, or single eye, is less convex than the cornea 

 of the latter ; while the chamber of the eye, or space between the cornea and the termina- 

 tion of the nerve at the bottom of the structure, is of much greater length in the com- 



* Memoires pour servir a l'Histoire des Insectes, tome vi. part. i. p. 98. 12mo. Amsterdam, 1748. 

 t Memoires, tome ii. part. 2. p. 887-8. pi. 30. fig. 23-25. 

 VOL. XXI. K 



