PHASES IN THE LIFE HISTORY OF NON-BITING FLIES 131 



These flies are necrophagous and deposit their eggs upon any fresh, 

 decaying or cooked meat, and upon dead insects ; they breed occasionally 

 in human excrement and sometimes will deposit their eggs in open flesh 

 wounds. On the battle fronts of Europe and Asia where the wounded lay 

 for long periods and where many dead bodies remained uncared for, these 

 flies multiplied to tremendous numbers and were largely responsible for 

 the carrying of infections to wounds. When a fly lays its eggs in living 

 flesh and the larvas develop therein, the infection is called myiasis. This 

 subject is of such importance that two entire lectures is devoted to it 

 (Chapters XII and XIII). 



Important as they are, the blow flies are usually subordinated to 

 the house fly in the discussion of dangerous flies, but thorough investi- 

 gations of these species are more than likely to greatly increase their 

 standing as disease carriers. 



The eggs are deposited in masses of as many as 300 and a single 

 fly may possibly deposit three batches. They hatch in from 10 to 24 

 hours after deposition. 



The larvas of C. erythrocephala may be distinguished from the house 

 fly larvae by having usually nine but sometimes up to twelve lobes in the 

 anterior (thoracic) spiracles; an anterior scabrous swollen ring on each 

 of the first eight segments of the abdomen, and a ventral groove on 

 each segment beneath; the stigmal field concave, surrounded by three 

 pair of tubercles above, and two large and one small pair below ; the 

 stigmal plates about once and a fourth their diameter apart, each with 

 three straight slits, directed principally toward the opposite plate; and 

 also, by having an anal pair of tubercles. The larval characters are 

 illustrated by Hewitt and also by Banks. 



The larval period requires seven and a half to eight days at 23° C. 

 (73.5° F.) and the pupal period fourteen days, according to Hewitt. 

 Bishopp and Laake found the larvae to attain full growth in three to four 

 days and the time from deposition of eggs to emergence of adults was 15 

 to 20 days. 



THE SHEEP MAGGOTS OK GREEN BOTTLE FLIES 



The European sheep maggot fly, Lucilia sericata Meigen, is primarily 

 an outdoor fly but occasionally is found indoors, especially in farm and 

 country houses. It is more brilliant than the Calliphoras, being of a 

 burnished gold with a shining, bluish-green color. The flies are strongly 

 attracted to meat and carcasses in which they lay their eggs. They 

 also occur on human and animal excrement. The larva breed readily 

 in all these substances. In Europe the flies very commonly lay their 

 eggs in matted wool and on the flesh on the backs of sheep, and the larvs 



