May, 1914.] The Cheese Skipper. 315 



experiment was closed with 22 dead flies in the jar; 16 (one of 

 which was dead) females in the fresh lean meat vial ; 6 live flies in 

 the fat fresh meat vial, none in the fat bacon vial, none in the 

 lean bacon vial, 6 9 s, 3 cf s, (4 of which were dead) in the fat ham 

 vial, 2 dead males were found in the lean ham vial, 3 9s and 1 

 dead male in the cheese vial. Many eggs were fomid in the fresh 

 lean and fat steak vials, the fat ham vial and the cheese vial. It 

 would seem from this experiment that the lean fresh steak, pos- 

 sessing a slightly putrid odor has a greater attraction for the flies 

 than the other substances used. 



SUMMARY. 



The cheese skipper because of its ravages on cheeses and smok- 

 ed meats and its possible relation to myiasis is of considerable 

 economic importance. 



The fly deposits its eggs upon bacon, cheeses, smoked ham, 

 slightly putrid beef -steak. Duration of egg stage 23 to 54 hours. 



Larvee feed upon bacon, cheese, ham, beef, oleomargarine. 

 This insect gets its common name from the peculiar leaping or 

 skipping habit of the larva. Duration of larval instar 14 days. 



Pupation occurs in dryer places than those in which the larvee 

 feed. Duration of pupal stage 12 days. 



The flies, in an experiment, seemed to prefer beef -steak with 

 a slight putrid order, in preference to ham, bacon or cheese, for 

 egg deposition. The adult flies lived longer, and the larvse fed and 

 matured more readily, on the beef steak than on the other sub- 

 stances. 



EXPLANATION OF PLATE XIV. 



Adult iiv about 8 times natural size. 



Profile of head of fly X 20. 



Lateral view of egg X 50, g. c. gelatinous cap. 



Dorsal view of egg X 50. 



Egg after emergence of larva. . 



Immature larva X 50. 



Mature larva X 5. 



Lateral view of caudal end of larva X 40, p. t., posterior tubercle; 



p. sp. posterior spiracle, d. t. dorsal tubercle. 

 Posterior view of Caudal spiracle X 400. 

 Dorsal view of caudal end of larva X 35; 1. an. lateral angular 



projections, d. t. dorsal tubercle, p. t. posterior tubercle. 

 Ventral view of caudal end of larva X 35. 

 View of posterior end of larva X 40, Sp. t. dorsal tubercles, p. sp. 



posterior spiracles, 1. an. lateral angular projections, p. t. 



posterior tubercles. 

 Lateral view of anterior end of larva X 50, a. sp. anterior spiracle, 



a. antenna. 

 Mouth parts much enlarged, m. s. mandibular sclerites, h. s. hypo- 



stomal sclerites, 1. p. lateral pharyngeal sclerites, d. p. s. 



dorsal pharyngeal sclerites. 

 Dorsal view of puparium X 8; d. t. dorsal tubercle, p. sp. posterior 



respiratory organ, p. t. posterior tubercle. 

 Pupal case after emergence of fly. 



Ohio Experiment vStation. 



