October, ’20] FENTON AND. HARTZELL: POTATO LEAFHOPPER 
403 
Summer Flight 
A general summer migration from early to late potatoes was observed 
in July. This took place over a considerable period of time, depending 
partly on the condition of the potato vines. In fields that had burned 
badly there was an early flight to either late potatoes or to fields in 
which many vines were still green. Otherwise this summer flight did 
not take place until late in July. That this was primarily not a forced 
migration because of lack of food plants was shown by the fact that it 
occurred in fields where there were still many green plants. Several 
fields were noted where, because of an especially severe infestation, the 
flight had been early, thus giving the vines a chance to send up vigorous 
sprouts. These were infested by adults from other fields that had 
burned late. However, in due time, no matter whether the vines were 
still green, the migration or mating flight was begun. It was evidenced 
at first by the swarming of the males at electric lights in the evening. 
In our experimental plots a row of Green Mountain potatoes, which 
had been practically free from infestation because the plants were not 
up at the time of the spring flight, received the first exodus from the 
surrounding early planted fields. This visitation was short, lasting 
only three or four days, but it was long enough to cause the vines to 
burn quite badly. Almost in a night, however, the hoppers disap¬ 
peared from these vines and began their summer dispersal flight to 
late potato fields, leaving only a few scattered immature individuals. 
A few days later adult hoppers again appeared on these plants coming 
in from the surrounding fields. 
This summer migration differed from the earlier spring flight princi¬ 
pally in that it occurred over a longer period of time. This apparent 
difference may be explained by the fact that the earlier summer 
flights were due to lack of food and that the real migration and sexual 
flight took place as suddenly as it did in the spring. The highest 
temperatures of the season were recorded at this date but there was 
no rainfall. 
How Long Do the Overwintered Adults Live? 
Shortly after their appearance on the potato vines, eleven pairs of 
adult hoppers were placed in small cages for longevity records, while 
about fifty were collected and placed in a large wire cage as a check. 
The first female of the eleven pairs was observed dead July 9, most of 
them dying between July 21 and 23, while one lived until August 4. 
Similar records were obtained from the large cage, and July 26 all the 
hoppers in this were dead. 
Further evidence that these females did not live much longer than 
late July was obtained by caging adults collected in the field at this 
