154 



DII'TEUA UF MINNESOTA. 



dcalli. This species is about one-third of an inch loni;-, metallic 

 Screen, with red^lish eves, resenililinu' a little the Green Bottle, but 



I'ig;. 148. Tlie Screw -worm ]'"ly, enlargcil. Lugger. 



with three dark stripes on the dorsal part of the thorax, sec Fig. 148. 

 "Althoug'h this fly is found in Minnesota, fortunately it does not ap- 

 pear to commonly attack man in the northern states. The egg is 

 one-sixteenth of an inch long, yellowish ; it hatches a few hours after 

 being laid. The maggot, when full grown, is three-fourths of an 

 inch long, tapering toward one end, with the posterior end trun- 

 cated. Tt gets its name of "screw-worm" from the fact that a ring 

 of bristles runs around its body between each segment, causing a 

 fancied resemblance to the thread of a screw. From four to six 

 days after hatching it becomes full grown. At this time it leaves 

 its food, and goes into the ground to pupate. Tn about seven days 

 the fly emerges. 



The Screws-worm Fly attacks also sheep, horses and hogs. Weed 

 sa>s that in the case of hogs the chief point of attack is the ears. 

 The odor arising from catarrhal conditions in man appear to attract 

 it, and we have several instances in this country of the fly laying 

 its eggs in the nostrils of man sleeping in the daytime out of doors, 

 causing disastrous results. Dr. Howard Md. Morton of Minneapo- 



