PAIRING OF INSECTS. 213 



of the mandibles will be found very slender, bulged 

 out at the base, and destitute of furrows. In making 

 experiments arid observations on this interesting fa- 

 mily, it will be useful to keep this distinction in mind, 

 as the neglect of it must often lead to erroneous 

 inferences with respect to their economy. 



In another interesting bee (Anthophora retusa), 

 one of the masons, the distinction of the sexes is so 

 great that some naturalists of high name have de- 

 scribed them as different species. The male is all 

 black, except the hind thighs, which have an orange 

 stripe ; while the female is grey, and has the middle 

 pair of feet fringed with long hairs *. This would 

 be one of the best species for ascertaining the interest 

 which the male takes in constructing the nest, 

 whether it be required to be mined into a sand-bank, 

 or the mortar of walls, as it frequently is, or 

 whether it has to be built from the foundation with 

 clay and other materials, as we have more than once 

 seen it, or whether both operations be required to 

 complete the structure. When first disclosed in the 

 early spring, we have remarked that the old nests 

 are as much frequented by the black males as by 

 the grey females, but we have never had the good 

 fortune to witness either of them at work. We have 

 also* remarked that the males are much more nu- 

 merous than the females f. 



Many other insects have the sexes marked by dif- 

 ferent colours ; though this will not hold as a general 

 rule, for the greater number are not so distinguished. 

 As in the instance of the bee just mentioned, the 

 different colours of male and female butterflies misled 

 Linnaeus into the opinion that they were not only of 

 different species, but of different families, and in 

 many instances his two divisions of Trojans and 



* See Insect Architecture, p. 84. for figure of female. 

 t J.R. 



