Vol. XXV] ENTOMOLOGICAL NEWS. 319 



cher also says, "All of the species so far as their habits are 

 known are oligotropic" (Can. Ent., 46: 51.) 



"The species are mostly very small." The length seldom 

 exceeds 6 mm., and in some species is only 2^ to 3 mm. 

 "They do not take long flights." So far as my observations 

 go, they settle quickly and may be easily captured without a 

 net. A part of the species are vernal ; but the majority fly in 

 late summer and autumn, and many visit the Compositae. A 

 very large number have been found in only one State, ap- 

 proximately 74 in New Mexico (34 in the Mesilla Valley), 11 

 in Texas, 3 in Arizona, 14 in Colorado, 3 in Nevada, 2 in New 

 Jersey, i in New England, and 6 in Mexico. About a dozen 

 have been reported from more than one State, P. octomaciilata 

 of the East having the widest distribution. Oligotropism is 

 as fully developed or, as the data available show, more pro- 

 nounced, where there is only one or few species as where there 

 are many. This habit cannot, therefore, be dependent on ex- 

 isting competition between the different species. 



Many flowers are visited by more than one species of Per- 

 dita; Salix by 2 ; Prosopis by 2 ; Mentselia by i at Santa Fe, 

 and 2 others at Albuquerque; Gutierrezia by 6; Solidago by 4 

 in Colorado, by another in New Mexico, and in New England 

 by a sixth species ; while Bigelovia ivrightii, which is "won- 

 derfully attractive to many kinds of insects" furnished 12 spe- 

 cies, etc. This behavior on the part of so many species of 

 Perdita and other insects is very similar to that of higher 

 forms of life when they gather at some feeding ground where 

 there is a superabundance of food. The flowers visited by 

 these bees occur in immense profusion and include the best 

 honey plants of this country, as Salix, Solidago, Cleome, Pro- 

 sopis, Hclianthus, Verbesina, Bidens aristosa and Monarda 

 punctata, a most valuable plant to beekeepers. It is note- 

 worthy that we find these flowers also visited by oligotropic 

 bees belonging to other genera. 



The presence or absence of many species of Perdita. espe- 

 cially in the case of the Compositae, is determined by the 

 length of the tongue. Cockerell states that the length of the 



