crystalline cone (field lens) and along the 
ommatidia to protect the sensitive instrument 
from the tremendous output of IR associated 
with the incandescent or mercury lamp. 
In any measurement of eye sensitivity, we 
would have to take into consideration this con- 
tinuous shift from one end of the spectrum to 
the other. The visible part of the spectrum 
covers only 1 octave, but the IR covers 17 and 
the ultraviolet 6 octaves, The human eye covers 
only the single visible octave. The complexity 
of a moth's eye incovering 24 octaves staggers 
the imagination ! 
A system of nighttime vision would certainly 
be greatly affected by the moon. Not only does 
a full moon with its visible light partially light- 
condition the eye (Callahan 1965c, table 2), but 
also, like the incandescent lamp, it emits 
tremendous amounts of IR radiation, although 
the latter may be blocked by the O, band around 
the earth (Pettit and Nicholson 1930), 
In our search for IR detectors, a third in- 
sect organ requires investigation. Histological 
preparations of the adult and larval corn ear- 
worm ocelli indicate that morphologically the 
ocelli of both stages have the configuration of 
an IR immersed detector. The domed cornea 
of the adult ocellus measures 28 uw across by 
22 uw vertically, The rhabdomeres are 28 u 
across by 10 uw deep. An immersed detector 
has a small active receptor mounted at the 
center plano part of a domed lens. Therefore, 
the ocellus would be ideally suited as an im- 
mersed detector for pickup of IR radiation 
from large, close sources, e.g., a plant or 
plant parts. Since the optic is a total unit, 
there would be no particular reason to assume 
that the IR source could be scanned by the 
organ either mosaically or mechanically. The 
behavior of many lepidopterous larvae in 
scanning with the head from side to side could 
indicate a search for incandescent or reflected 
point sources of IR plant radiation. 
SOME EXPERIMENTAL EVIDENCE 
OF TRANSMISSION AND 
DETECTION BY MOTHS 
To test some of my theories, I conducted 
some preliminary experiments. A behavioral 
characteristic of both noctuid and sphingid 
moths is the "warmup" of wings before flight 
163 
(fig. 6). Among the noctuids, such behavior 
does not necessarily always precede flight and 
is often accomplished without regard to flight. 
A female corn earworm moth invariably vi- 
brates her wings during courtship. Wing vibra- 
tions are accompanied by a tremendous gen- 
eration of heat and thus by a high FIR signal. 
To record this signal, I had the company 
manufacturing the Barnes ® IR bolometer 
(fig. 7) focus the IT-2 model to a distance of 
10 inches. A small 29-gage hypodermic therm- 
istor probe was inserted in the intersegmental 
membrane between the mesothorax and the 
metathorax of the test moth, and the moth 
mounted on the probe in front of the bolometer 
sensing head (fig. 8), The hypodermic probe 
was connected through a _ telethermometer 
amplified to the bottom vertical display of a 
dual-beam oscilloscope. The IR bolometer, 
with a field of view of 0.54 inch’ at 30 spread, 
was aimed at the moth's thorax. The output of 
the bolometer postamplifier was connected to 
the top vertical display of the oscilloscope. In 
several of the experiments an air probe was 
connected to the bottom display beam for a 
check on the background ambient temperature 
of the laboratory. As the various moths vi- 
brated their wings, their internal thoracic 

Figure 6,--Corn earworm moth vibrating its wings just 
prior to takeoff, This flight vibration has high wing 
stroke amplitude compared with low amplitude vibra- 
tions often observed in resting moths with wings held 
rooflike over back, Both types of wing vibration prob- 
ably enter into FIR signaling and detection, 
