DIPTERA OF MINNESOTA. 145 



size in this family, and strikingly enough, the "halteres" or balancers 



are small in proportion as the "alulae" are large. 



THE HOUSE FLY. 



Ahisca domestica. 



Found practically over the entire world ; lays its eggs in piles 

 of horse manure, or, in the absence of this preferred larval food, in 

 other filth, one female depositing as many as i6o eggs. In twenty- 

 four hours the egg hatches, and the life of the maggot or larva is 

 from five to seven days. It then changes to a pupa, the skin of the 

 larva hardening to form a brown pupa case or puparium, and after 

 from five to seven days the perfect fly emerges. 



When cold weather comes, some adults hibernate in protected 

 situations indoors and out, and emerge at the arrival of the first 

 warm days in spring, only to hide in their retreats again if the weath- 

 er becomes cold. Cold weather occurring during the breeding sea- 

 son, retards development, and it is claimed that this fly can winter 

 in the pupal stage. Late summer brings to the adult fly diseases in 

 the shape of fungi, which attack and kill them ; small mites fasten them- 

 selves upon them, either as parasites' or for transportation and at all 

 times in the summer they are the legitimate prey of the dragon flies, 

 wasps and other predatory animals. 



At least one of the disgusting habits of this spe- 

 cies has been referred to on a previous page, in dis- 

 cussing the family, and no careful housekeeper is 

 going to allow house flies about the food in the 

 house. A darkened pantry is not disturbed by flies. 

 As is well known, typhoid fever is caused by a 

 germ which, at a certain stage of the disease, is 

 known to be present in the excreta of patients. 

 Since these, or closely, allied germs, may be present 

 i-'ig. 138. Maggot and somctimcs in fsecal matter of parties not necessar- 

 F^y.^From °Packard '^^Y showiug symptoms of the disease, and since the 

 common house fly is a frequenter of such filth, 

 the need of hygienic methods in the environment of the farm house 

 need not be emphasized further. Privies should be covered, or 



