February '21] 



hartzell: potato leafhopper 



T.\BLE III. — Longevity of Summer Generation Fem.\les 



67 



OVIPOSITION 



Owing to the minute size of the egg and its concealment in the plant 

 tissue, it is impossible to make egg counts. In order to determine 

 the number of fertile eggs, potato plants were exposed to females for seven 

 day periods and the number of nymphs hatching noted. The plants 

 used in this experiment were grown in the greenhouse where they had 

 been free from exposure to leaf hoppers. 



From June 21 to September 6, for a period of seventy-seven days 

 first generation nymphs were hatched from eggs deposited by overwinter- 

 ing females. Nearly twelve weeks elapsed from the time the first nymphs 

 hatched until the last ones appeared in the cages from these overwinter- 

 ing individuals. 



T.\bi,e IV'. — Number of Xvmphs H.\tched from Eggs Deposited by Overwintering Fem.\les 

 C.\PTURED After Spring Flight 



The females introduced into the cages prior to the spring flight 

 averaged 34 nymphs, while those introduced after the flight average 

 88 nymphs. It appears that the early appearing females had laid part 

 of their eggs the previous sumrrier before going into hibernation. The 

 maximum number of nymphs reared from eggs deposited by a single 

 individual was 142. This record was obtained from a female captured 

 at the time of the spring flight. This female also holds the longevity 

 record for overwintering individuals, living until August 27. 



The early appearing nymphs of the summer generation hatched in 

 our cages July 30 but did not appear in any numbers imtil the middle 

 of the month. The last nymph of this series hatched October 22 but 

 young were collected on curly dock as late as October 28. Thus the 

 oviposition period extended from the middle of July to the middle of 

 October for this season. The greatest number of nymphs reared from 

 eggs deposited by a single female of the summer generation was 59 as 



