maximum corm earworm activity (Callahan 
1958), 
Consider the following three factors; (1) The 
peak wavelength of a black night sky is ata 
maximum in the 10-y region; (2) green plants 
have an extremely high emissivity and could 
thus emit as tremendous incandescent sources; 
and (3) the emissivity of a plowed field (table 1) 
is extremely low and could reflect considerable 
IR radiation. The only conclusion that one can 
reach is that a freshly plowed field with young 
corn plants might present contrasting shades 
of light and dark radiation resembling that of 
a lighted city to the occupants of an airplane. 
To a moth having an eye operating as a night- 
time IR detector, especially if such an eye 
can detect a range from 1 to 18 yw, the corn- 
field might present a remarkable pattern for 
identification. If the moth flies high, the case 
for IR plant detection becomes even stronger, 
for it then could detect row after row of plants 
with high IR incandescence at an emissivity of 
0.97 against a freshly plowed field with a con- 
trasting emissivity of 0.28. 
There is no longer any doubt that sphingids 
and noctuids fly at a height between 20 and 150 
feet. Releases of 9,000 corn earworm moths 
color coded with phosphorescent powders pro- 
duced a return catch of 18 moths in a black- 
light trap. The moths were released at 1/4, 
1/2, 1 mile, and 2 miles, The farthest releases 
were in areas with pine forests between the 
release point and light trap, All returncatches 
were taken at 4 a.m., within 9 hours of the 
previous evening's releases. Immediately on 
release, moths that flew at all flew to heights 
ranging between 25 and 150 feet. 
Roeder and Treat (1961) obtained flight 
photographs of night-flying moths avoiding 
bats and only a few appeared to be flying at 
the level of a corn plant. I have watched 
sphingid moths through binoculars "homing-in" 
from above 100 feet or so on our night-lighted 
greenhouse. Activity recordings in the labo- 
ratory indicated that although noctuids were 
relatively inactive during the night in which 
they emerged, most of their flight activity 
took place during the first 4 or Snights of life. 
This is apparently a time of intense roaming 
on the part of the noctuid species. 
Research by plant scientists using aerial 
IR photography of plants has shown that the 
mesophyll layer of a leaf reflects considerable 
171 

IR radiation. Reflection is reduced in diseased 
or dried leaf tissue and the difference can be 
detected by infrared film. The radiation emis- 
sion and reflection of IR from a sick or dried 
plant would change so drastically that, in my 
opinion, the change might well account for in- 
creased attraction of moths to healthy plants. 
It is a well-established fact that when it has a 
choice, the corn earworm seeks fresh silks 
and avoids dry silks for oviposition. 
IR ENVIRONMENT AND HOST 
PLANT RESISTANCE 
My theories of the insect environment raise 
some interesting questions in regard to host- 
plant resistance. Does a resistant plant gen- 
erate a significantly different IR emission or 
a significantly different IR reflection than a 
susceptible plant? 
Figure 13 compares an IR tape blackbody, 
a corn leaf, and the silk of a susceptible and 
a resistant variety of corn. The analyses 
Block Tope 
81 | Whorl 
Leat Susceptible 
Stowell’s Evergreen 
Silks Susceptible 
Wolters White 
Silks Resistant 
MICRONS 
Figure 13,--IR spectrum of black tape blackbody and 
leaf and silks of some corn varieties, Note that silk 
from susceptible variety has stronger absorbance in 
9- region than silk of resistant variety, These bands 
are in 8- to 13=uwindow, 
