serious pest of livestock and wildlife. It is 
now being used to get rid of the same pest 
in Texas and New Mexico, and, for all practical 
purposes, the job has been done. However, 
screw-worms can and do migrate fromnearby 
Mexico, Thus, we are continuing the program 
in the Southwest to prevent reinfestation. 
In both program, the insects were sterilized 
by exposing them to gamma radiation from a 
radioactive cobalt source. More recently, we 
have made good progress in finding chemicals 
that will sterilize insects without otherwise 
affecting their behavior. House flies, mos- 
quitoes, and boll weevils have been safely and 
effectively sterilized. We're already using 
chemosterilants to control the Mexican fruit 
fly population on the California-Mexico border, 
We hope to devise techniques for placing 
chemosterilants within reach of some of our 
most important insects, They would, in effect, 
treat themselves. 
The sterile male technique for controlling 
pests--using irradiation or chemosterilants-- 
does not represent a widespread weapon at 
the present time. But as we work out better 
ways to use the technique alone or in combi- 
nation with others, we believe it will become 
a major and highly effective weapon in the 
future. Chemosterilants, particularly, will be 
more widely utilized, we feel, as we develop 
and use attractants as a means of exposing 
insects to these chemical compounds, 
The use of natural and synthetic insect 
attractants offers almost unlimited opportuni- 
ties for controlling pests. This is not a par- 
ticularly new approach. We've worked with 
attractants of one kind or another for many 
years. Their heightened appeal at this time 
lies in the fact that we are finding some new 
and highly active attractants, and are improv- 
ing our techniques for using and evaluating 
them. 
We've recently developed protein hydrol- 
ysate bait sprays for tropical fruit flies; 
granular and other baits for house flies; 
mirex with bait for fire ants. And, in one of 
the outstanding recent achievements of ento- 
mology research, we eradicated the Oriental 
fruit fly from the Pacific island of Rota by 
using a sex attractant--which drew the insects 
from a considerable distance--along with an 
insecticide--which actually killed them. Me- 
61 
chanical traps, pathogens, or sterilants are 
equally effective in destroying pests in this 
situation. 
Certain kinds of light show promise in con- 
trolling insects, particularly those that fly 
long distances, such as some of the tobacco, 
cotton, and cabbage pests. We trapped tobacco 
hornworms in an area of 113 square miles in 
North Carolina for 3 years in succession, 
using near ultraviolet light. By so doing, we 
reduced the population of this pest by 90 per- 
cent. The use of light was coupled with the 
destruction of tobacco stalks late in the fall. 
We have been able to utilize other forms of 
light as well as sound and radio waves to con- 
trol insects on anexperimental basis. We found 
that the larvae of certain insects are inter- 
rupted in their development when they are sub- 
jected to flashes of light, even as small as 
1/1000th of a second. We have experimented 
with radiofrequency electromagnetic fields in 
controlling grain insects... and feel this is 
a promising technique. 
Another highly desirable and economical 
non-chemical approach is to breed plants that 
are resistant to certain diseases and other 
pests. There's a great deal we can do to fully 
exploit this practical approach. Research re- 
sources in the past have rarely been adequate 
to take on both the short-term work needed to 
solve immediate problems and the long-range 
exploration needed to develop this technique. 
Yet, in instances where aconcerted research 
effort was made, we've been able to develop 
varieties resistant to disease andinsect attack. 
The development of wilt-resistant alfalfa va- 
rieties and others that resist the spotted 
alfalfa aphid is an outstanding example. Good 
progress has been made in breeding corn 
hybrids resistant to diseases, such as smut 
and stalk rot, and to insects such as the 
European corn borer. We have sugarbeets 
resistant to curly top, potatoes that resist 
leaf roll, and numerous varieties of winter 
wheats resistant to various strains of rustand 
to insects such as the Hessian fly. Plant breed- 
ing along with pesticides has contributed to a 
reduction in damage from nematodes--one of 
our most devastating pests. 
It is interesting to note that Australians 
have reported cattle strains that appear to 
resist the cattle fever tick. 
