NORTH AMERICAN SYRPHIDJl. 



PART I.-OLASSIFICATION. 



The family of Syrphidce is one of the most extensive in the order of 

 diptera. Nearly or quite two thousand species are known from through- 

 out the world, and mauy new forms are constantly being added. They 

 contain among them many of the brightest-colored flies, and numerous 

 specimens are sure to appear in every general collection of insects. 

 None are injurious in their habits to man's economy, and many of them 

 are very beneficial. In the following pages about three hundred 

 species are described from the region north of Mexico, so that I trust 

 even the non-entomological student, with a little exertion, may be able 

 to identify them. That there are many more species within these limits 

 is certain, especially in the southern and western regions. From Europe 

 over five hundred and fifty species have been catalogued; doubtless 

 nearly or quite as many will be eventually accredited to ¥orth America. 



The family is easily and exactly defined ; with but few exceptions by 

 the presence of the spurious vein of the wings alone ; in all, by the struct- 

 ure of the head and the ne uration. Its position in the dipterological 

 system is thus given by Brauer : 



Saborder Ctcloeehapha. 



Section Aschiza. Section Schizophorida. 



Tribe Syrphidm. Tribe Hypocera. Tribe Eumidce. Tribe Pupipara. 



{Syrphidce, s. str., Pipunculidce.) {Phoridce, Platypezidce.) 



Schizometopia. Holometopia. 



(Muscidoe ealyptratce.) (Muscidce acalyptratce.) 



While, as a general rule, the Syrphidw present excellent specific 

 characters, there is a remarkable dearth of generic or group characters. 

 The richness in species, the many intermediate forms, the absence of 

 marked plastic variations, all tend to make the family in its subdivis- 

 ions an exceedingly difficult one to define with clearness. From this 

 fusion or coalescence of genera, we are often compelled to base our classi- 

 fication upon what appear very trivial differences. Species must be 

 grouped together that show natural relationships, drawing the divid- 

 ing lines where the largest intervals occur. Their classification ulti- 



