( clxxvi ) 



to it among the Aculeates : — viz. Apis mellifica (the Hive 

 Bee) ; Anthidium moMicatum, Anthoj)hora acervorum (Solitary 

 Bees) ; and Methoca ichneumonides (a Fossorial Wasp, which 

 was formerly reckoned among the Ants). He then proceeds 

 as follows : — " The explanation of this anomaly is that a 

 marriage-flight is absolutely necessary with these species, and 

 the male requires great strength and size in order to carry 

 the female through the air." * 



For the credit of Hymenopterists I am sorry to say that 

 the specialist consulted by Darwin did not state the facts cor- 

 rectly. The (^ (? of the Hive Bee and of Anthoplwra acervorum 

 are 7iot larger than their $ ? ! f The premises being partly 

 wrong, it is not surprising if the conclusion be unsatisfactory : 

 and I must own that Darwin's explanation — if indeed it be 

 Darwin's, and not, like the premises, received by him from 

 F. Smith — appears to me quite untenable. If he had had 

 the complete facts before him, I feel sure he would have 

 concluded, that — certainly in Anthidium and almost certainly 

 in Methoca — the character selected by Nature was not large- 

 ness in the male but smallness in the female : and that the 

 explanation of these exceptions to the general rule had 

 nothing to do with the so-called " marriage-flight." 



First let me state the actual facts. — In two Fossorial 

 Genera, viz. Methoca and Myrmosa, and also in several 

 species of the allied genus MiUilla, the size of both sexes 

 (but the $ $ especially) differs much in individuals, but the 

 (J (^ on an average are certainly far larger than their $ $, and 

 the latter (as compared with average ? ? in the same Family) 

 are generally rather dwarfish insects. Again, in Anthidium 

 manicatum, and also in most of the larger (but N.B. not in 

 the smaller) species of the same genus, the $ ^ vary in size 

 enormously, but the 9 ? very little ; — the largest $ $ are 

 about as large as the smallest (^ i^, but their maximum size 

 never reaches the average size of the other sex. 



Prima facie these facts seem to me to suggest, that great 



* Descent of Man (Second Edition), p. 279. 



f Of course the Hive-bee Drone is larger than the Worker, but his 

 true Female (the Queen) is larger still. The sexes of A. acervorum (i.e. 

 pilipes) differ little in size, but on comparing a long series of both sexes 

 I find the 9 ? on an average a little larger than their i S • 



