NOTES ON HYMENOPTERA. 81 



Take the case of the wasp : it is certain that all the wasps 

 developed in spring are, in the larval condition, dependent 

 upon a single wasp, the queen, for nourishment, and all these 

 are workers ; the males on the contrary are produced in 

 autumn, when the nest is most populous and food most 

 abundant. 



Among solitary bees I have observed, that those belonging 

 to the genus Colletes frequently arrive at their perfect con- 

 dition without having consumed the whole of the food stored 

 up for them ; I am unable to say which sex was developed 

 from such cells, but here was a superabundant supply ; I 

 have not noticed a similar occurrence in the nest of any 

 other bee. 



The case of the genus Anthidlum is remarkable, and ap- 

 pears to be strongly opposed to the theoiy of Landois. The 

 males, in this genus, are always much larger than the 

 females; the male carries off the female and copulates in the 

 air; many males are twice the size of the females; in this 

 case, it would certainly appear that the males would require 

 even a larger quantity of food than the females. 



Let us also take into account the economy of a fossorial 

 and also a vespidious insect. The genus Cerceris is an 

 example of the former group; now some of the species of 

 this genus store up rhyncophorous beetles ; in this case, both 

 sexes are undoubtedly supplied with food of the same quality, 

 when in the larva state. 



Among the solitary wasps, we find the genus Odynerus 

 storing up a number of caterpillars, all certainly those of the 

 same species of moth. 



The theory of Professor Siebold, that of parthenogenesis, 

 is applicable to the development of all the Hymenopterous 

 insects whose economy I have investigated, whilst that of 

 Landois is certainly not; the objections to it appear to me to 



1869. G 



