Vo I. 9, No. 6 
Page 7 
not indicate that a suduen, significant die-off of mice had occurred after 
insecticide treatment in either field. Although no evidence of mammal mortality 
could be detected, the parathion treatment provided adequate control of alfalfa 
weeviIs. 
Although parathion is more toxic to vertebrates than most chlorinated- 
hydrocarbon insecticides, it does not persist in the ecosystem long after 
application as do the chlorinated hydrocarbons. Since this experiment has 
indicated no overt mortality to small mammals, the use of the more toxic but non 
persistent parathion may be more desirable than use of chlorinated-hydrocarbon 
insecticides which have persistent, far-reaching and insidious effects upon 
populations of wild vertebrates. 
