290 



HOUSEHOLD INSECTS 



Fig. 97. — Cheese skip 

 per, maggot of P. casei 

 (X5.) 



on the life history of the cheese skipper in the summer of 

 1892. She found that the egg was pearly white, slightly 



curved, and one-twenty-fifth of an 

 inch in length. The eggs may be 

 deposited in more or less compact 

 clusters of five to fifteen or they may 

 be laid singly in folds of the wrapping 

 cloth. The eggs hatch in thirty-six 

 hours and the minute slender larvae 

 go at once in search of food. The 

 larva, or " skipper, " is cylindrical, tapers gradually toward 

 the anterior end but is truncate at the posterior end (Fig. 

 97). Projecting from the posterior end are two horny stig- 

 mata and a pair of fleshy filaments. 

 The maggots attain their full growth in 

 seven to eight days, becoming about 

 one-third of an inch long. While feed- 

 ing, if there is an abundant supply of 

 food, the larvae do not move about 

 much. When they become full-grown, 

 however, each one crawls to a crack or 

 crevice in the fold of the wrapper and 

 there contracts and changes to a pupa 

 (Fig. 98). The pupal stage occupies 

 about ten days. Thus in August the 

 life cycle would be passed in three FlG - 98 

 weeks. 



Kellogg also studied the life history 

 of this insect during February and March of the same 

 year. He found at this time of year that the egg stage 

 occupied about four days and that the larvae were about 

 two weeks in completing their growth. The pupal stage 



Pupa of 

 cheese skipper, 

 enlarged. 



