THE CHEESE SKIPPER AS A PEST IN CURED MEATS 



19 



other as 1 is to 3.6; in other words, fecundity is here very nearly 

 in direct proportion to longevity. 



During hot weather the usual reproductive period is brief. 

 Weather sufficiently cool to delay the beginning of oviposition to the 

 second day after mating seems to be advantageous to fecundity, 

 since it enables more feeding prior to egg laying; and this delayed 

 egg laying, and the lessened general activity in cool weather, 

 apparently prolong life. In the case of the group of females mated 

 on September 27, 1922, the cool weather continued and the tempera- 

 ture was such as to allow the females to have the advantage of a 

 recuperative period after their first heavy egg laying and to develop 

 a second series of eggs. Females which laid 200 or more eggs 

 typically show comparatively long egg records, the eggs laid being 

 divided more or less definitely into two groups, but hot weather 

 usually results in the exhaustion of the vitality of the females after 

 five or six days. 



Parthenogenesis has not been observed. Virgin females seem to 

 lay about as well as mated females but all of their eggs fail to hatch. 

 Table 7 gives oviposition records of unmated females. 



Table 7. — Oviposition of virgin females 1 of Piophila casei at Washington, D. C, 



in 1922 



Female No. 



Date 

 emerged 



Number of eggs laid on— 



Length 

 of life 



Total 





Oct. 2 



Oct. 3 



Oct. 4 



Oct. 5 



Oct. 6 



Oct. 7 Oct. 8 



Oct. 9 



eggs 



1 



Nov. 1 

 1 

 1 

 1 

 1 

 1 

 1 

 1 

 1 



77 







61 



80 



71 







50 



36 



31 









 81 







25 



94 







Days 

 6 

 13 

 6 

 20 

 19 

 16 

 21 

 16 

 7 



273 



2 







106 



3 









HI 



4 







33 







6 







41 



190 



5 







6 



5 

 

 

 



53 



25 



57 

 74 





 



6 

 



52 

 







19 



32 





142 



7 



44 



8 







57 



9 







79 











153 















Total 





223 



366 



31 



193 



77 



113 



32 



41 











13.8 



119.5 

























* These females were given fresh ham on November 1 and were kept at laboratory temperatures. Rel- 

 ative humidities in the room had little reference to the humidities in the vials, which contained moist 

 meat. During the oviposition the daily mean temperatures were all about 70° F. None of the eggs laid 

 by unfertilized females hatched. 



Several experiments were made to determine the approximate 

 maximum temperature at which reproduction takes place. Pairs in- 

 cubated at a constant temperature of 104° F. did not reproduce, 

 whereas those in a temperature of 102.2° F. reproduced abundantly. 

 The indications of all trials are that the maximum temperature for 

 reproduction lies between 102.2 and 104° F. 



- OVIPOSITION PERIOD AND POSTOVIPOSITION PERIOD 



As is shown by the data in Tables 2 and 4, eggs are frequently laid 

 within the first 24-hour period after mating. This is especially true 

 of the records in Table 2 which includes records obtained in an ab- 

 normally hot summer. The first batch of eggs is as a rule larger 

 than subsequent ones. Eggs are usually laid on three or four dif- 

 ferent days and during the oviposition period, the time from first 



