Tne influence of migrant moths moving into the trapped area in obscuring 
the total effect of the trapping operations cannot be fully assessed on the 
basis of data now available. The data suggest, however, that some additional 
reduction in hornworm moth populations above that achieved in this experiment 
could be expected, if traps of a like density were operating in an area of 
sufficient size to eliminate the influence of migrant moths. To appraise the 
significance of moth migration, it will be necessary to conduct experiments in 
larger areas or on the total population in an isolated situation such as an 
island. 
Further experiments in different seasons to study higher or lower popula- 
tion densities and the effect of variable factors affecting hornworm avundance 
and survival in different areas must be undertaken to make a reasonable 
appraisal of the degree of control that will result from the use of light traps. 
A change in cultural practices or a general reduction in the use of 
insecticides could lead to the survival of a higher percentage of the eggs and 
larvae that are produced by fewer moths, which could negate the influence of 
the trapping operation. 
Irrespective of the influence of such variable factors, however, the results 
of the first full year of study in a relatively large area are regarded as 
encouraging. They certainly justify further investigations with every indica- 
tion that the operation of light traps, integrated with other necessary control 
procedures, could materially contribute to more efficient tobacco hornworm 
control. 
SUMMARY 
A series of experiments were conducted in North Carolina in 1961-62 to test 
the effect of traps on populations of the hornworms Protoparce sexta (Johannson) 
and P. quinquemaculata (Haworth). 
Traps using iso-amyl salicylate as a bait and spaced at quarter-mile 
intervals in an area of 3.14 square miles caught the most hornworms of both 
species in open fields and on the top of hills and caught nothing in wooded 
areas except at the edge. The mean catch for the season was very low in 
comparison with that for light traps and zero for the first 2 weeks. 
When 14 light traps were scattered over 25 square miles and moths were 
marked and released, they dispersed rapidly in all directions. Many flew 3 to 
4 miles in one night, and recaptures were made as far away as 8.2 miles. Five 
percent of the males of P. sexta moved 4.89 miles. When about three light 
traps per square mile were placed in a circular area 12 miles in diameter with 
a few check traps outside the circle, the mean catch increased gradually from 
the center of the circle outward to at least 6 miles beyond the edge. The 
percent reductions in population at the center were 76 and 89 for males of 
P. sexta and P. quingquemaculata and 55 and 58 for females. There was no 
difference in the fertility of the females. The reduction in populations of 
eggs and small larvae on tobacco between 9-12 and O-3 miles from the center of 
the trapped area was 50 percent. This reduction was not statistically 
Significant. 
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