18 



BULLETIN 1453, IT. S. DEPARTMENT OF AGRICULTURE 



Table 5. — Daily mean temperatures in 1922 in laboratory at Washington, D. €!., 

 ichere the experiments on Piophila casei shown in Table J t icere made. 



[Based on daily average of thermograph readings taken at two-hour intervals] 



Date 



°F. 



Aug. 29 



75 



30 



74 



31 



76 



Sept. 1 



76 



2 



75 



3 



75 



4 



79 



5 



80 



6 



80 



7 



80 



8 



76 



9 



77 



10 



78 



11 



79 



12 



77 



• 13 



73 



14 



74 



15 



77 



10 



78 



17 



70 



Date 



Sept. 18. 

 19. 

 20. 

 21. 

 22. 

 23. 

 24. 

 25. 



Oct. 



27 



28 



29 



30.... 



1 



2.... 



3 



4 



5 



62 



72 



Date 



Oct. 8 

 9 

 10 

 11 

 12 

 13 

 14 

 15 

 18 

 17 

 18 

 19 

 20 

 21 

 22 

 23 

 24 

 25 

 26 

 27 



65 



Date 



Nov 



Oct. 28. 

 29. 

 30- 

 31. 

 1_ 

 2_ 

 3_ 

 4_ 

 5_ 



Date 



Nov. 17- 

 18- 

 19. 

 20- 

 21- 

 22. 

 23. 

 24- 

 25 _ 

 26. 

 27. 

 28. 

 29. 

 30. 



Dec. 1. 

 2. 

 3. 



A general impression gained from the experiments reported in 

 Tables 2 and 4, in which temperature was the only apparent variable 

 of importance, is that very hot weather is not optimum for the 

 oviposition of P. casei. That the mating instinct wanes during 

 extremely hot weather has been previously noted, and the rapidity 

 of expenditure of energy under such conditions shortens life. Larval 

 growth, however, is most rapid during the hottest weather, as is 

 also the process of metamorphosis within the puparium. 



In Table 4 the pairs which were mated September 27 were supe- 

 rior in fecundity to all other groups, although the temperatures 

 which they experienced were not unusually high. Table 6 presents 

 a comparison of data relating to the first nine pairs mated Septem- 

 ber 27 with those of the group immediately preceding, which 

 emerged and were mated September 4. Not enough insects are in- 

 volved in this comparison to justify the drawing of conclusions, but 

 the indications are of interest. 



Table 6. — Comparison of conditions influencing the fecundity of certain females 

 of Phophila casei recorded in Table J/ 



Number of pairs used in comparison. . . 

 Average longevity of females, in days... 

 Minimum longevity of females, in days. 

 Maximum longevity of females, in days 



Average number of eggs laid 



Minimum number of eggs laid 



Maximum number of eggs laid 



Average daily mean temperature (°F.)_ 



Minimum daily temperature (°F.) 



Maximum daily temperature (°F.) 



Pairs 



Pairs 



mated 



mated 



Sept. 4 



Sept. 27 



8 



9 



3.6 



13.8 



3 



6 



5 



19 



86 



306 



30 



133 



141 



480 



79 



69.4 



73 



59 



85 



79 



In the records in Table 6 the two average longevities are to each 

 other as 1 is to 3.8+ and the two oviposition averages are to each 



