(159) Food irradiation; FDA approves wheat, Nucle- 
onics 21 (10): 28, October 1963, 
(160) Irradiation ship would eliminate grain loss to 
insects in tropics, Nucleonics 19 (6): 88-89, 
June 1961, 
(161) Photoflash--entomologists use light to upset 
insect cycle, prevent dormant stage, Agr, 
Res, 13 (1): 3-4, July 1964, 
(162) Radiation preservation offood, U.S, Army Quar- 
termaster Corps, published by U,S, Govt, 
Printing Off,, Washington, D,C., Aug, 1, 
1957. 
(163) Response of insects to induced light--presenta- 
tion papers, U.S, Dept. Agr. ARS 20-10, 
July 1961, 
EXPERIMENTS ON THE CONTROL OF INSECT POPULATIONS 
WITH LIGHT TRAPS 
F, R, Lawson and Cecil R, Gentry, Entomology Research Division, 
and James M, Stanley, Agricultural Engineering Research Division, 
Agricultural Research Service, U.S, Department of Agriculture, Oxford, N.C., 
and Blacksburg, Va., respectively 
The primary purpose of these experiments 
was to find ways of controlling the hornworms 
that attack tobacco without using insecticides, 
The tobacco hornworm (Protoparce sexta 
(Johannson)) is a major pest of tobacco and 
tomatoes wherever these crops are grown in 
the United States, The tomato hornworm (P, 
quinquemaculata (Haworth)) attacks the same 
crops, but is much less numerous in most of 
the tobacco-growing areas, 
These investigations were conducted near 
Oxford, N.C,, in 1961-64, A description of the 
traps and data for 1961 and 1962 have been 
published elsewhere (Lawson et al, 1963 and 
Stanley et al. 1964), Additional data for 1963 
and 1964 and from similar experiments are 
reported in papers now in press (Gentry et al. 
and Hoffman and Lawson), This is a general 
account of the entire investigation, 

REVIEW OF LITERATURE 
The biology of the hornworms was dis- 
cussed by Gilmore (1938), Madden and Cham- 
berlin (1945), and Metcalf (1909), 
Frost (1952) reported that light traps had 
never been too successful in the control of 
injurious insects, He considered traps to be 
at best a supplementary measure, Much of the 
early work was done with daylight lamps or 
weak mercury-vapor lamps, In the 1940's the 
availability of improved lamps stimulated re- 
194 
search on light traps, and several reports on 
the control of various insects were published, 
Taylor and Deay (1950), working on the Euro- 
pean corn borer Ostrinia Nobilalis (Hubner)) in 
Indiana, used seven traps along the edge of 
cornfields, These were electrocutor gridtraps, 
some with 100-watt reflector mercury-vapor 
lamps and others with five 30-watt black-light 
fluorescent lamps, The population of borers 
was reduced 57,0 and 69.5 percent at distances 
of 153 and 87 feet, respectively, from the 
trap location, Damage from stalk breakage 
caused by the borers was reduced nearer the 
traps, This result substantially agreed with re- 
sults of earlier work with light traps by Ficht, 
Hienton, and Fore (1940), 
Pfrimmer, Lukefahr, and Hollingsworth 
(1955) found that four fan- and four gravity- 
type traps with black-light lamps were 
ineffective in reducing populations of the 
pink bollworm (Pectinophora gossypiella 
(Saunders)). There were indications that the 
traps were drawing the moths from distant 
parts of the fields, 
Noble, Glick, and Eitel (1956) reported no 
control of the corn earworm (Heliothis zea 
(Boddie)), the pink bollworm, and the cabbage 
looper (Trichoplusia ni (Hiibner)) in an ex- 
periment they conducted in Texas in an area 
covering about 3,000 acres where they operated 
142 light traps. Clogged electrocutor grids 
sometimes caused the traps to fail because of 
electrical shorting and, thus, to lose effective- 
ness, 

