Larval counts in the two fields appear similar, with neither 
becoming excessively high. The untrapped field was treated six 
times with insecticide during the season; the trapped field was 
treated four times. 
DISCUSSION 
The population of injurious lepidopterous insects was 
considered low in the Reeves County area in 1965, Advocates of 
light traps contend that this decrease was caused by the trap- 
ping system. However, oral reports by members of the Heliothis 
Research Exchange meeting in New Orleans, La., in December 1965 
indicated that the population density of H. zea was low through- 
out its distributional range. The best index to the relative 
population sizes of H. zea in Reeves County in recent years comes 
from figures of gross receipts of insecticides sold and applied 
by one of the more stable of the dealer-applicators of aerial 
insecticides. Assuming the company received its normal share of 
business, gross receipts from sales and services indicate that 
the 1965 bollworm population was only 35 percent as great as in 
163 and T9664, 
The fact that insect traps collect thousands of H. zea 
moths throughout the season cannot be denied. Depending upon 
the time of the year when nightly catches were counted, the 
numbers collected per trap varied from 0 to as many as 1,047 for 
a single night. Then if the catch for a trap-day is defined as 
the catch of bollworm moths for one 24-hour period in one insect 
trap, 1,635 trap-days were accumulated from July 18 to September 
6, 1965. During this time, an average of 151 H. zea moths were 
captured per trap per day. If each of the estimated 2,000 traps 
in the area removed the same number of H. zea moths per trap 
during the same 51 days, the total number of bollworm moths re- 
moved from the population would have approximated 15-1/2 million, 
or 335 moths per acre, This amounts to 7 moths per acre per day 
for the entire 46,000 acres of cotton. Of course, the same 
calculations for the 16,000 acres that were actually trapped 
indicate that the traps removed 15-1/2 million moths, or about 
960: moths per acre or 19 moths per acre pere@day. If one—halsn 
these H. zea moths were females each capable of ovipositing 200 
viable eggs, the traps removed a potential of 1,700 eggs per acre 
per day, or about 1 egs per 200 stalks of cotton perrday. 
The writer believes these data indicate that the 2,000 
electric insect traps operating in Reeves County, Texas, in 1965 
had an impact on the entire population of H. zea in the area 
rather than on populations in individual fields. That is, the 
estimated 15-1/2 million H. zea moths captured during 51 days in 
1965 probably were trapped from 46,000 acres of host plants 
rather than from the 16,000 trapped acres. 
14 
