252 THE CANADIAN ENTOMOLOGIST. 



6. Oncomyia, Robineau-Desvoid}'. 



1. Oncomyia abbreviaia, Loew. — One male from Sioux County, 

 Nebraska, May, on Oxytropis. The legs are black, except the base and 

 apex of hind femora, base of all the tibiae and metatarsi, which are yellow. 



2. Oncomyia Barofii, Williston. — Specimens from West Point, 

 Lincoln and Glen, Sioux County, Nebraska, which show considerable 

 variation in the coloration of the antennas and legs. 



3. Oncomyia loraria, Loew. — Two males from Lincoln, Nebraska, 

 which on account of their small size I btlieve should be placed here. 

 They agree with Loew's description, except that the lines of the thorax are 

 indistinct, and the second joint of the proboscis is not longer than the 

 first, but is about equal to it. Length, 3.5 mm. 



4. Oncomyia propinqua, Adams. — A male on Cleome and a female on 



Feiaiosiemoti, both from Glen, Sioux County, Nebraska, August, 1906 



(H. S. Smith). This species is evidently very close to 0. Baroni, if not a 



variety of it. It can be separated, however, by its more slender form, 



longer and more delicate proboscis, and more black colour in general. 



The legs are entirely black, except the extreme base of the tibiae, which is 



yellow. 



I. MvoPA, Fabricus. 



I. Myopa clausa, Loew. — Numerous specimens from Lincoln and 



Sioux County, Nebraska, April and May. The specimens vary from 5.5 



to 9.5 mm. in length, and show some colour variation also. 



PRACTICAL AND POPULAR ENTOMOLOGY.— No. 21. 



The Scolytid^ or Engraver-beetles. 



by j. w. swaine, ithaca, n. y. 



(Continued from page 195.) 



The Ambrosia- or Timber-beetles. —The Ambrosia- or Timber- 

 beetles breed entirely within the wood, the eggs of some species being laid 

 well within the heart-wood. There may be several secondary egg-tunnels 

 cut by two or more females, branching from a primary tunnel, which leads 

 from the common entrance hole. Rarely the tunnels of closely-allied 

 species branch from a common entrance hole. 



The number of males in this group is small, in some species there 

 being seldom more than one or two males in a brood of fifteen or twenty. 

 In many species the males are apterous, and the females are fertilized 

 before leaving the tunnels in the spring. Among the Bark-beetles the 

 males are apparently quite as numerous as the females. 



July, 1907 



