24 



DIPTERA OF MINNESOTA. 



maggot flies emerge. The maggots in the backs of cattle and the 

 maggot known as the hot of horses (the same being true of the 

 rabbit bot, found in the neck of rabbits) bore into the ground, 

 where they pass the pupal stage. The "flax seed" stage of the 

 Hessian Fly is the period in which the brown puparium of this 

 pest, resembling somewhat a flax seed, is found against the stem. 

 The puparium of the house fly is found in filth, notably horse 

 manure, where the egg is commonly laid, and where the maggot 

 lives. 



We have then, with a few exceptions, already noted, four stages 



■%£j^1 



Fig. 4. Side view of House Fly, Miisca domcstica. Original. 



in the life history of every fly, namely, the egg stage, the larval 

 or maggot stage, the pupal stage and the adult stage, or the stage 

 represented by the perfect fly in the winged condition. The adult 

 fly, as in other insects, is referred to as the imago. 



The structure of this "imago," or adult fly, since it is the con- 

 dition with which we very commonly become acquainted with flies, 

 deserves a short description. Fig. 4 illustrates the common house 

 fly, viewed from tlic right side, drawn with its right wing elevated 

 to enable one to sec the various parts of the insect. One will at 



