ZooL— Vol. III.] KELLOGG— NET-WINGED MIDGES. 215 



dangers of an extreme specialization. If the fixed pupag 

 lie in water too deep (easily occasioned by a sudden rise in 

 the stream at the time for emergence), or on the other hand, 

 become wholly bereft of the life-giving water by a falling 

 of the stream, there is no hope for the fly. The first 

 contingency seems indeed to be somewhat provided for (as 

 explained in the account, -postea, of the life-history of the 

 flies) by the apparent power of the insect of postponing for 

 some time, if necessary, its emergence. Thus, in the event 

 of a heavy rain and consequent rise of the stream, the too 

 deeply submerged pupa may lie unchanged until the water 

 has run off (a matter which happens speedily in swift 

 streams) to a safe shallowness. 



Imagines. — The fully developed flies were found numer- 

 ously in the case of but two of the six species whose larvae 

 and pup« are familiar to the writer. These two are 

 Blepharocera ca-pitata (Ithaca, New York) and Bibiocefhala 

 elegantiilus (Estes Park, Larimer County, Colorado). 

 Abundant as the larvae and pupae of the Californian species 

 are, and Bibiocephala cornstocki and B . doanei are really 

 abundant in half a dozen streams within easy reach of the 

 laboratory, but one free-flying B. cotnstocki and but three 

 or four B. doanei have been taken. Of Blepharocera 

 jordani, whose larvae and pupae are also not uncommon in 

 the same streams, but a single free fly has been taken. As 

 indicated in the descriptions of the new species, it has been 

 possible to get acquainted with the structural characters of 

 the adults by dissecting the flies out from the pupal cases, 

 but such methods are hardly available for a study of the 

 habits of the flies ! 



The flies of Blepharocera capitata were seen abundant 

 last summer (1901) on the banks of Cascadilla Creek, on 

 Cornell University Campus (Ithaca, New York). The flies 

 at rest cling by their long legs to the undersides of leaves on 

 the bank, from the water's edge to eight or ten feet away. 

 Of the hundreds of flies which were seen here in two or 

 three visits, all were females; and the chief business on 

 hand was feeding. This was accomplished by capturing 



