Several lines of research are needed inconnection with the use of chemicals. We have 
discussed the work being done on repellents for package treatments. We are now beginning 
to look also for repellents that might be applied to grain for protection against insect 
infestation during storage. Other potential uses for an effective repellent would be in 
warehouses, transportation facilities, or food plants. The searchfor repellents is challeng- 
ing because it may be possible tofind effective materials in groups of chemicals that lack 
mammalian toxicity. This would be another step towardavoiding pesticide residues. 
’ The search would be continued for effective pesticides with low toxicity to humans. 
At the same time we should be alert to take advantage of unique physical and chemical 
properties of compounds. There are intriguing possibilities for the use of vapor toxicity 
or a short residual life in the stored-product insect field. Other compounds that may be 
of interest are those that interfere with or interrupt normal insect growth, development, 
or reproduction. 
We believe it would be profitable to devote some more careful study to formulations 
and methods of application for the pesticides we are now using. If improved formulations 
were devised to produce increased effectiveness, less pesticide would be required to do the 
job and residue hazards would be reduced. Better application methods would reduce the 
possibilities of incidental contamination and increase the safety to operators. 
Finally, and perhaps most important of all, a great deal of basic research on the 
stored-product insects themselves is much needed, It is surprising to find how little is 
known about many of the species. Mostofthe information we have about the more common 
species was obtained under controlled laboratory conditions of constant temperature and 
humidity, often in the range optimum fortheinsects. There is little reason to assume that 
the biological functions of growth, development, reproduction, and behavior will be the 
same under these conditions as in the natural habitat. We should conduct ecological, life 
history, and behavior studies under the actual environmental conditions of the grain bin, 
elevator, warehouse, or food plant. Only then will we begin to learn how these insects 
really live. Also is needed some basic research on the reactions of these insects, their 
responses to various stimuli, competition and interaction between species, their migration 
or movement from place to place, sources of infestation, the ways and reasons infesta- 
tions originate, and the relationships between infestation and different commodities or 
different kinds of food supplies. As we learn more about the insects we will be able to 
devise better ways of protecting our food andother commodities against their ravages. 
INDUSTRIAL CHEMICAL CONTAMINATION OF LIVESTOCK FEEDS 
Aubrey M. Lee! 
The problems on industrial chemical contamination of livestock feeds will be dis- 
cussed in this paper. Excluded are the biological agents in the nature of viruses, bacteria, 
rickettsiae, parasites, and mycotic agents, which we know may contaminate livestock 
feed and about which we need so much more scientific research information. Also 
excluded are discussions on the contaminations of livestock feeds with chemicals that 
are poisonous because of biological and chemical activities within the soil, plant, and 
animal. These numerous exclusions are as important and, in most cases, more im- 
portant than industrial chemical contamination of livestock feeds as far as the health of 
farm animals are concerned. They are too numerous to mention but some include several 
trace minerals, especially selenium and molybdenum, and the currently important 
1Head, Noninfectious Diseases Section, Animal Disease and Parasite Research Division, Agricultural Research Service, U. S, 
Department of Agriculture, 
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