NOTES ON PSITHYRUS. 27 



Psithyrus ashtoni. The comb consisted of numerous empty 

 Bremus and Psithyrus cocoons and a large quantity of Psithyrus 

 brood in various stages of development. This colony was kept 

 under observation until September 26. From August 9 until Sep- 

 tember 14 the nest was examined at least twice a day. Once a 

 week every worker was caught, so that the young Psithyri, which 

 had hatched during the preceding week, could be collected without 

 incurring the wrath of the colony. Thereupon the young Psithyri 

 were placed in a box and fed with honey and pollen until their pile 

 attained its full color. In this way 29 males and 61 females of 

 Ps. ashtoni were collected from this Bremus-Psithyrus colony, but 

 a considerable number of males, and perhaps a few females, prob- 

 ably made their escape during the last few days preceding the 

 weekly collections. 



Despite the fact that the abdomen of the B remits queen was 

 much distended, and that she was seen to lay eggs on August 10 

 and on subsequent days, not a single Bremus queen, male, or 

 worker hatched. As the nights became colder during the early 

 part of September, the affinis-ashtoni colony, which by this time 

 had dwindled down to about a dozen individuals, gradually died off. 

 On September 12 the old Psithyrus queen was found dead in the 

 nest, two days later the Bremus queen was missing, and the last 

 worker died on September 26. 



In this case the Psithyrus queen must have gained admittance to 

 the affinis nest during or before the first few days of July. The 

 Psithyrus and the Bremus queen, therefore, lived together for at 

 least two months. During the time they were under observation 

 (August 9 to September 12) the two queens did not show the least 

 antagonism, nor did any of the other members of this Brcmus- 

 Psithyrus colony exhibit the slightest sign of hostility toward each 

 other. 



The fact that no young bees developed from the eggs laid by the 

 Bremus queen corroborates similar observations by Hoffer ('88) 1 



i This author ('88, p. 101) reports two exceptions to this rule. On Sep- 

 tember i, 1880, he took home a nest of Bremus variabilis Schmiedeknecht 

 containing the old queen and 15 workers of B. variabilis, and 8 females and 

 10 males of Psithyrus campestris Panzer. During the next few days, 4 more 

 males and 9 females of Ps. campestris, and 2 males and 3 females of B. 



