indirect and is not yet very convincing. It in- 
cludes; (a) Observations of the fact that moths 
can raise their body temperature several 
degrees above ambient temperature by physical 
activity, such as wing beating; (b) bodies at 
these temperatures give rise to infrared radia- 
tion at wavelengths corresponding to a trans- 
mission window in the atmospheric absorption 
curve for infrared radiation; and (c) configura- 
tion and dimensions of the fine structure of 
moth antennae indicate that parts of the an- 
tennae might serve as infrared receptors at 
wavelengths corresponding to those radiated 
by the moths. Structure of the compound eye 
of the corn earworm moth (Heliothis zea 
(Boddie)) has also been analyzed, with theidea 
that it could function as an infrared receptor 
for detection of far infrared radiation and 
image formation (32). 
Extensive and difficult experimental work 
will be required to settle the question of the 
radiation theory of communication in insects. 
If it should be confirmed, in any way, however, 
new control measures using’ infrared energy 
may be possible. 
Infrared technology has developed rapidly 
in recent years because of its significance as 
a passive detection method and emphasis on 
military applications. Instrumentation for in- 
frared research is now being developed that 
will permit interesting investigations relating 
to possible pest-control methods. 
Visible and Ultraviolet 
Visible radiation refers to that part of the 
electromagnetic spectrum to which the human 
eye is sensitive, i.e., the region from some- 
what below 4,000 to somewhat below 8,000 
Angstrom units (A.). The range of response 
for insects, however, extends into the ultra- 
violet region to somewhat below 3,000 A. 
(68), and, whereas human visual acuity peaks 
at about 5,560 A., peak response of many 
insects occurs in the near ultraviolet at about 
3,650 A. (74, 77, 146, 148). Some insect 
species have shown peak responses to light 
in the 4,900- to 5,200-A. range (68, 74, 75, 77, 
131, 146, 147, 148). In some cases, the latter 
range was a secondary peak, and in some the 
primary peak depending on light intensity. 
Physiological as well as physical and other 
180 
factors influence the phototaxis of insects 
(48, 69, 88, 108, 132, 163), 
There is a vast amount of scientific litera- 
ture dealing with visible and ultraviolet radia- 
tion and its relation to insects. From the 
standpoint of pest control, insect traps using 
light sources as attractants are probably the 
best example of practical application for this 
type of electromagnetic radiation (64, 73, 76). 
Most commonly used insect light traps employ 
a blacklight fluorescent lamp as the attracting 
source. These lamps emit strongly in the 
ultraviolet region, with peak emissions in the 
3,500- to 3,800-A, range, and attract large 
numbers of insects of photopositive species. 
Insects attracted to the lamps are trapped in 
a collection device, usually a funnel and con- 
tainer, which is mounted below the lamp. Var- 
ious trap designs have been developed for 
particular purposes (64, 76), and numerous 
experiments have been conducted to determine 
the most attractive lamps for particular in- 
sects (17, 43, 65, 67, 83, 113, 163). 
In recent years, light traps have come into 
widespread use as an entomological survey 
device, and as such have been extremely use- 
ful in overall insect-control programs, Light 
traps are now used extensively for detection 
and quarantine work (18, 66, 133). They have 
also been helpful in detecting population 
changes and in predicting potential insect 
infestations and need for control measures 
(66, 94, 109, 115, 121). Information on insect 
light-trap collections at various locations 
throughout the United States is currently 
tabulated and published weekly for the benefit 
of entomologists concerned with insect-control 
problems.t 
Use of insect light traps for direct control 
has been of interest to a few scientists for 
many years (49, 64, 95, 107, 114, 127, 128, 
134). Light traps afforded some protection 
from insect damage to vegetable crops in 
garden-plot studies (42, 43). In the last few 
years, results of a large area study on direct 
control of tobacco hornworms (Protoparce 
sexta (Johannson)) using blacklight traps have 
been encouraging (129). In 1962, with a trap 
density of three traps per square mile over a 
1 Cooperative Economic Insect Report, issued by 
Plant Pest Control Division,. Agricultural Research 
Service, U.S, Department of Agriculture, 

