pests, to determine insect population changes or trends, and in predicting 
potential infestations. They may eventually prove useful in the control of 
insect pests. 
Light traps using ultraviolet or black light lamps are being used in 
experiments for attracting tobacco hornworm moths, by ARS entomologists 
and agricultural engineers. In a 113-square mile areain North Carolina 370 
traps caught, in 1962, an estimated 50 to 60 percent of the adult moths in 
the area. 
Other well-known insects which are attracted in the adult stage by 
artificial light include the codling moth, oriental fruit moth, corn earworm, 
various cutworms, fall armyworm, cabbage looper, cotton leafworm, 
European corn borer, European chafer, and pink bollworm. 
In small-plot tests, Indiana and ARS scientists found that the yield of 
sweet corn undamaged by the corn earworm was significantly higher in 
plots where electric light traps were used than in check plots. Tomato 
hornworm infestation was reduced in plots with electric light traps. 
Insect-Resistant Plants 
The growing of crop varieties that are resistant to insects is a highly 
desirable means of pest control that has been used for many years. This 
method can be used without extra costtothe grower, without creating insec- 
ticide residues that might be harmful to man and domestic animals or wild- 
life, and without causing damage to parasites, predators or pollinating 
insects. 
While breeding resistant crops seems an ideal approach to insect 
control, there are some difficulties in this method. 
It usually takes several years to developavariety resistant to one pest, 
and much longer to incorporate multiple resistances toa complex of insects 
and diseases which must be controlled on a single crop. Furthermore, our 
agriculture requires different varieties for the different geographic areas. 
Therefore, variety development must be done on not just one but several 
lines. 
Add to this the necessity of having good agronomic and other charac- 
teristics as well as pest resistance. The resistant germplasm often is 
found in wild plant species or noncommercial breeding stocks, which intro- 
duce unacceptable characters as well as the resistance into the new lines. 
It sometimes takes many generations of breeding to eliminate the undesir- 
able characters and reincorporate the best characters of existing commer- 
cial varieties, while retaining the new resistance. A resistant but otherwise 
poor strain, such as some of our earworm-resistant breeding lines of sweet 
corn, is worthless for commercial production. 
Crop Varieties with Insect Resistance 
There are insect-resistant varieties, strains, or hybrids of many crops, 
including alfalfa, apples, beans, cabbage, celery, clover, corn, cotton, cran- 
berries, grapes, grapefruit, grass, oats, potatoes, rice, sorghum, sugarcane, 
turnips, vetch, and wheat. Some of these are suitable for use in breeding 
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