256 THE ENTOMOLOGIST, 



experience, and also to that of every hymenopterist whom I 

 have consulted. jMalcs and females are developed in the 

 autumn alone, and, as I believe, only a single brood in the 

 same nest dining the season. The number of bees forming 

 the autumnal colonies, when nests contain all the sexes, and 

 when they are most numerously populated, is greatly depen- 

 dent upon the kind of season wlien they are examined : if 

 the season has been fine, dry and hot, colonies will reach 

 their maximum ; but a wet season has a contrary effect. A 

 populous colony of Bombus senilis would not contain less 

 than two hundred bees, probably about twenty being females, 

 forty males, and the rest worker or neuter bees. 



The smallest colonies appear to be those of Bombus Syl- 

 varum and B. fragrans ; those of B. jNIiiscorum usually the 

 largest : these remarks apply solely to the surface-building 

 bees. 



The nests of under-ground builders are much more popu- 

 lous, and the majority of them are a pugnacious and 

 courageous race : Bombus terrestris and B. lapidarius resist 

 an attack upon their citadel with the well-known impetuosity 

 and determination of a wasp or hornet, whilst nests of Bora- 

 bus Latreillellus may be dug out with impunity. The most 

 populous communities, as far as ray experience enables rae 

 . to judge, are those of B. terrestris and B. Lucorum. 



My own researches have led me to the following con- 

 clusions : — Humble bees have only one brood during the 

 season : a single female, that has passed the previous winter 

 in a state of torpidity, is the foundress of the colony ; for 

 some time workers only are developed in the nest, but, as 

 autumn approaches, the other sexes appear : towards the 

 end of autumn all the community quit the nest ; the females, 

 being impregnated, to seek for some secure place in which to 

 hyberuate during the winter j the males and working bees, to 

 perish. 



The time at which the different species complete their 

 labours differs in various species ; thus B. Pratorum usually 

 completes her task earlier than any other species : males 

 sometimes appear at the end of May, whilst that sex of B. 

 terrestris, and of the majority of the other species, are not 

 found until the latter part of August. 



It has been stated that if a male Bombus once leaves the 



