332 



O. E. PLATH. 



Julv ii. Meanwhile several fervidus workers had hatched, and, 

 beginning July 13, the colony was allowed to forage in the open. 

 For a time, this borealis-fervidus colony seemed to get along very 

 well, but on July 19, it was noticed that the fervidus workers 

 kept the borealis queen from the comb most of the time by daub- 

 ing her with honey, a habit which has been described in another 

 paper ('220). In spite of this treatment, the queen lingered about 

 the nest until August 18, when she died. During the first part 

 of August, several fervidus males hatched in this nest, but no 

 adult borealis were obtained from any of these mixed colonies. 



As has been pointed out in another paper ('226), practically 

 nothing is known concerning the nesting habits of this species. 



Pratorum GROUP. 



I. Bremus bimaculatus Cresson. 



After losing several bimaculatus queens through dueling, a 

 queen of this species was confined alone on May 20. Two days 

 later, a bimaculatus worker was given to her, but she squirted the 

 latter with faeces, 1 and showed her hostility in other ways. On 

 the following day, another bimaculatus worker was substituted 

 for the first. With this second worker she soon became friendly, 

 and by the next morning a honey-pot and a cell containing eggs 

 were present in the nest. On May 26, two more bimaculatus 

 w r orkers were added to this nucleus. The first batch of larvae- 

 twelve in number grew rapidly and began spinning their co- 

 coons about June 7, and the first adult a male emerged on June 

 18. The bees which hatched from the remaining eleven cocoons, 

 as well as those which emerged later, were likewise males. It is 

 evident, therefore, that this bimaculatus queen had not been 

 fertilized the preceding fall, and that, in some instances, bum- 

 blebee males may be produced as early in spring as workers, a 

 fact which has been overlooked by other bumblebee students 

 (cf. Dahlbom ('32, pp. 9, 10), Schmiedeknecht ('78, pp. 317, 320, 

 323), Hoffer ('82/83, p. 15), Wagner '07, p. 126), Sladen ('12, p. 

 49), and Stellwaag ('15, pp. 466, 467)). 



1 This method of warfare is also employed by the queens and workers of other 

 American species, e.g., Bremus impatiens. In Europe, Wagner ('07, p. 82) observed 

 a similar behavior in the case of Bremus variabilis, a queen of this species squirting 

 the liquid for a distance of more than 35 cm. 



