or methemoglobinemia. Its higher toxicity to 
avian species is presumably due to their more 
rapid rate of metabolism in comparison to 
mammals. Our interest in the compound 
stemmed from industry data on its differential 
in toxicity to laboratory rats and domestic 
chickens, Although this avicide is highly toxic 
to a number of avian species, its hazard to 
them can be controlled. For example, the bait- 
ing of starlings at northern livestock feedlots 
is carried out during winter months after most 
other birds have completed their southern 
migration and prior to their return in the 
spring. 
The present program for control of the 
lamprey in the Great Lakes illustrates chemi- 
cal selectivity in an aquatic environment. 
More than 6,000 compounds were tested by the 
Bureau of Commercial Fisheries in its search 
for an effective material. The work resulted 
in discovery of the lampricide TFM (3- 
trifluoromethyl-4-nitrophenol), Atlevels of 1 
to 17 p.p.m., depending on the chemistry of 
the water, it is highly lethalto lamprey larvae. 
These concentrations have little effect on most 
other forms of aquatic life in treated streams, 
The previously mentioned fish toxicant, anti- 
mycin, is another example of how selective 
control of certain species can be achieved in 
aquatic habitats. 
Most of the vertebrate pesticides in use, 
including those recently developed, are toxic 
to vertebrates of many species, although the 
exact lethal dose may vary. They owe their 
usefulness to man's technical ability to devise 
safeguards for beneficial species occupying 
the same habitat. For example, by carefully 
controlling the concentration of strychnine in 
baits, a treated grain can be produced that 
will kill field mice and ground squirrels, but 
quail, pheasants, and domestic poultry can 
consume it without lethal effect. The mourning 
doves that might also feed on the grain are 
endangered by these rodent-control levels of 
strychnine. This problem is corrected by 
changing both the shape and color of the grain, 
to which change doves and many small seed- 
eating birds show an avoidance reaction. 
Similar devices of formulation, placement, and 
timing have evolved a margin of safety for 
beneficial species over the many years of 
strychnine use. Such techniques must rely on 
careful programing by the user, which is not 
always possible when control chemicals are 
placed in the hands of untrained or careless 
individuals, This margin of error, small as it 
may be, is the basis for much of the current 
concern about the hazards of broad-spectrum 
pesticides. 
Competing forms of life take advantage of 
man's every step to increase the production 
of food and fiber. Through the many changes 
we have wrought, we can no longer rely on 
antiquated methods for protection from pests. 
Our need for chemical tools will grow. Selec- 
tive lethal agents, chemosterilants, synthetic 
attractants, and systemic repellents now loom 
on the horizon. They exemplify the versatility 
of modern chemical technology. We must make 
greater use of that field of science in the 
development of better methods for pest con- 
trol, 
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Applegate, Vernon C,, John H, Howell, and Manning A, 
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