THE POTATO TUBER MOTH. 27 



Table 6. — Oviposition of the potato tuber moth by virgin females. 



Female No. 



Period 

 between 



emerg- 

 ence an.d 



ovi- 

 position. 



Total 



number 



eggs. 



Period 

 of ovi- 

 position. 



Length 

 of life. 



1 



Bays. 

 5 

 1 

 3 

 7 

 4 

 5 

 5 

 4 



13 

 51 



6 

 44 



1 



18 

 29 



9 





 32 



Bays.. 



1 

 5 

 9 

 1 

 16 

 13 

 6 



Bays. 

 17 



2 



13 



22 



- . 11 



21 

 18 

 12 



28 

 17 



2 



3 



4 



5 



6 



7 



8 . . . . 



9 



10 



6 



10 





Examination of this table will show also that oviposition was 

 delayed longer after emergence than in the case of fertilized females. 



POSSIBLE PARTHENOGENESIS. 



To corroborate the observations on parthenogenesis cited by 

 Picard regarding this insect (83), unfertilized females were isolated 

 dm-ing spring and fall, and all the eggs deposited were carefully 

 watched. In these experiments 54 females deposited a total of 

 486 eggs, of which 324 were laid during September and 162 during 

 April and May. None of the eggs hatched, showing that while 

 parthenogenesis may exist, it is not very common. 



LENGTH OF LIFE. 



Pairs of adults isolated proved that the length of life of the male 

 is shorter than that of the female. This proved to be the case in 221 

 out of 275 experiments carried out for egg records. In nearly every 

 case where the female died first the egg record was poor, indicating 

 that the female was abnormal to begin with. The length of life 

 varies with the temperature, the warmest season giving the shortest 

 life records. This is even more pronounced where the adults are 

 not fed. 



The extremes noted for length of life were, for the male 1 to 14 

 days, and for the female 2 to 22 days, in cases where the pairs had 

 mated. In experiments using unmated individuals the length of life 

 for the male varied from 3 to 31 days, and for the female, 2 to 28 days. 



In the case of the male which lived 31 days no food was given, and 

 tlie individual was kept in a dry vial. This record was made during 

 November when the weather was cool. 



