THE CARROT RUST FLY 15 



Table 12. Period of oviposition of the carrot rust fly 

 First Generation, VValtham, Mass. 1928-1930. 



When flies were confined in lantern globe cages at constant temperatures, it 

 was apparent that temperatures below 70° F. were much more favorable than 

 higher ones. 



Table 13. Relation of constant temperature to the life and oviposition 

 of the carrot rust fly 



First Generation, W'altham, Mass. 1931. 



Constant 

 Temperature 



55° F. 

 65° F. 

 75° F. 

 85° F. 



♦Reproduction ratio is determined by multiplying the average length of life by the average 

 number of eggs laid. 



Incubation of Eggs 



In the insectary studies, the eggs were placed on damp blotting paper in shallow 

 covered glass dishes or on blocks of plaster of Paris set on moist sand, and under 

 these conditions from 55 to 95 percent of the eggs hatched. As shown in Table 

 14, the period of incubation ranged from 3 to 17 days, and averaged 6.17 to 9.70 

 days. 



Table 14. Incubation period of the carrot rust fly eggs 

 First Generation, Waltham, Mass. 1928-1930. 



The length of the incubation period and the number of larvae which hatch 

 are dependent upon temperature. This was first indicated in 1930 when 20 eggs 

 placed in the greenhouse where the temperature ranged from 70° to 105° F. failed 



