THE ROLE OF CHEMICALS FOR THE CONTROL OF VERTEBRATE PESTS 
Walter W. Dykstra, Research Staff Specialist, and Robert E, Lennon, Chief, Fish Control 
Laboratories, Bureau of Sport Fisheries and Wildlife, Fish and Wildlife Service, U.S. 
Department of the Interior, Washington, D.C,, and LaCrosse, Wis., respectively 
Toxic substances have a long history of use 
by mankind as a means of capturing wild 
animals for food, Primitive peoples in South 
America and Southeast Asia applied mashed 
cube or derris root, which contains rotenone, 
to fresh and salt waters to stun and kill fish. 
Similarly Malaysian tribes used the derris 
root as an ingredient of arrow poisons 
(Leonard, 1939), The early Chinese used 
"fishing plants,'' particularly ''tea-seed cake" 
made from the saponin-bearing seeds of 
camellia, to kill fish in ponds (Tang, 1961), 
The use of walnut hulls to immobilize and 
capture fish has also had a long history (West- 
fall et al., 1961). 
TERRESTRIAL VERTEBRATES 
It was a short step for man to extend his 
use of naturally occurring toxic materials to 
the destruction of animals that interfered with 
his interests. The early use of toxicants is 
evidenced by ancient Egyptian hieroglyphics 
depicting a bulb of the red squill plant along- 
side a dead rat. The drawing suggests that the 
rodenticidal properties of squill were known 
thousands of years ago. The toxic nature of 
strychnine was known to the Old World during 
the 1600's, According to one early writer, 
"The chiefest use that they are put unto is to 
kill Dogs and Cats, and other creatures by 
mixing some of it with meat, as also to give 
unto Crowes, Ravens, and other such-like 
troublesome birds that by their noyse dis- 
quiet mans sleepe or studies" (Young and 
Goldman, 1944, p. 323), Numerous other his- 
torical accounts lead one to suspect that our 
knowledge concerning the lethal properties of 
arsenic and strychnine is in part due to their 
use to eliminate individuals of another species 
of vertebrate, Homo sapiens. 
Although circumstances surrounding the 
origin of some economic poisons are obscure, 
it appears that man's early knowledge of toxic 
substances was largely limited to afew botani- 

29 
cals and naturally occurring minerals. The 
fact that they were found to be lethal to one 
species of animal provided the clue that they 
might also produce similar effects on other 
creatures, Through trial and error by indi- 
viduals confronted with animal pest problems, 
their use was spread to more and more species. 
This is illustrated by the early history of 
strychnine for the control of terrestrial ver- 
tebrates in North America. It was widely used 
by early settlers to destroy gray wolves that 
preyed upon their livestock, Large amounts 
were also employed by trappers to facilitate 
the collection of furbearers for their pelts. 
According to Young and Goldman (1944), 
sometime about 1848 a shipment of strychnine 
was consigned from Philadelphia to a South 
American port, but news of the gold dis- 
coveries in California reached the vessel and 
the cargo was landed at San Francisco. The 
strychnine was sold there and used for the 
control of harmful animals. By the turn of 
the century it was applied extensively through- 
out the West for the control of predatory 
animals, rabbits, field andcommensal rodents, 
and nuisance birds, 
In 1912, the Bureau of Biological Survey 
initiated a program for the control of ground 
squirrels in national forests in California. 
During 1915, this activity was expanded to in- 
clude predatory animals. The first Government 
laboratory to conduct research on lethal agents 
for the control of wild vertebrates was estab- 
lished at Albuquerque, N. Mex,, in 1920 and 
moved to Denver in 1922, This laboratory was 
the predecessor of the present Denver Wildlife 
Research Center of the Bureau of Sport Fish- 
eries and Wildlife. During the intervening 
years up to the present, the major part of the 
research on methods for controlling damage 
by wildlife has been carried out at that loca- 
tion. One of the laboratory's first accom- 
plishments was the development of a scent 
containing oil of catnip as an attractant for 
trapping feline predatory animals. Now, some 
40 years later, chemical attractants are still 
