22 DIPTERA OF MINNESOTA. 



of SiinitJiiclae. We have not hesitated, therefore, to ask for co-opera- 

 tion wherever needed, and have called upon specialists in certain 

 groups for identifications. These have been cheerfully given. 

 Many of the Empidids and Dolichopods were identified by W. M. 

 Wheeler; Stratiomyids and Leptids by C. W. Johnson; Phorids 

 by C. T. Brues, and the snarl in the condition of our Simuliids was 

 unraveled by C). A. Johannsen. We have sent many specimens 

 to Mr. Coquillet of the Bureau of Entomology at Washington, for 

 corroboration of our own identifications, or for the independent 

 naming of specimens, and a large amount of material from this 

 office has passed through his hands. The colored drawings have 

 all been made in this department, and under our direction, by Miss 

 Edith Reed. The same is true of a very large proportion of the 

 figures in the text. A few of the latter, however, have been used 

 in previous publications of this department, and a very few have 

 been obtained from outside sources. Fig. 150 is one of Prof. 

 Slingerland's ; Fig. 29 was obtained from Vernon Kellogg ; Figs. 

 34 and 35 appeared in "How to Make a Flower Garden " published 

 by Doubleday Page & Co., Fig. 36 was obtained from the Depart- 

 ment of Agriculture at Washington, D. C, and is one of Dr. L. 

 O. Howard's. We hereby acknowledge these courtesies. Many 

 of the photographs were made by Mr A. G. Ruggles, my assistant. 



A large amount of dipterous material, representing many 

 months of collecting, was kindly placed at our disposal through 

 the courtesy of O. W. Oestlund, of the Department of Zoology in 

 the State University. This has been of material help. Dr. E. B. 

 Frick, of Fort Snelling has collected certain Culicids not previously 

 in our collection, and has courteously given us data in this con- 

 nection. 



The word "Fly" in common parlance, is frequently applied 

 to almost everything in the insect line which has the power of 

 flight. It really belongs only to one order of insects, the Diptera, 

 in which only one pair of wings (the front pair) is present, the 

 rear pair being absent, but represented by two "halteres" or 

 "balancers," knob-like organs to which various functions are 

 ascribed by workers in entomology. We have in North America 

 over 8,000 known species of these two-winged flies, representing 

 sixty families, and in the following pages these various families 



