BREEDING EXPERIMENTS WITH BREMUS QUEENS. 339 



Another pennsylvanicus queen was therefore put in her place on 

 June 5. Although hostile to the fervidus workers, queen No. 2 

 constructed an egg-cell and oviposited on June n. But, as in 

 the case of the fervidus nuclei, the larvae were not fed and died 

 shortly after hatching. Both Bremus fervidus and Bremus penn- 

 sylvanicus are Pocket-makers, i.e., they feed their larvae, at least 

 those of the workers, 1 through one or more pockets which they 

 make at the side of each group of larvae. On returning from the 

 field, the foraging bee deposits its load of pollen directly into 

 these pockets, through which the latter reaches the larvae. It 

 seems probable, therefore, that the Pocket-makers let their 

 worker larva? die, whenever they cannot feed them in the usual 

 way. If this supposition is correct, it will be impossible to rear 

 colo'nies of the Pocket-makers from confined queens, unless the 

 latter are permitted to collect pollen from flowers. 



Since the methods employed in rearing colonies of other species 

 yielded no results in the case of Bremus fervidus and Bremus 

 pennsylvanicus, and as I was anxious to obtain a colony of the 

 latter species, a different method was resorted to. On June 26, 

 about a dozen cocoons of Bremus impatiens were given to penn- 

 sylvanicus queen No. 2, which she adopted immediately. She 

 showed no hostility toward the young workers which emerged, 

 and two days later constructed an egg-cell and laid a batch of eggs. 

 On July 2, this mixed colony was placed out of doors so that the 

 workers could forage. Everything went well until July 6, when the 

 queen was found dead in the nest, having probably been killed by 

 the impatiens workers. 



On July 26, a third pennsylvanicus queen was confined with 

 a pennsylvanicMs worker and sixteen cocoons of Bremus fervidus, 

 and on August 2, another pennsylvanicus worker was added to 

 this nucleus. The cocoons were adopted immediately, as were 

 the fervidus workers which hatched from them. On August 3, 

 the queen built an egg-cell and oviposited, and two days later 

 this fervidus-pennsylvanicus colony was given its liberty. Penn- 

 sylvanicus worker No. I did not return, but No. 2 and several of 

 the fervidus workers brought in one load of food after another. 



1 The queen and male larvae of Bremus fervidus, and probably also those of Bremus 

 pennsylvanicus, are fed, at least toward the end of their development, like the 

 larvae of those bumblebees which do not feed their larva? through pockets. 



