15 



E. Range Insect Control 



Over 6,000,000 acres were treated in 1957 to control grasshopper and 

 Moraon cricket outbreaks in range and crop lands. Tens of millions of acres 

 are at times infested with these pests and large control programs are conducted. 

 Bureau personnel have summarized the effects of aldrin or heptachlor - 0.125 to 

 0.25 pound per acre; chlordan - 0.5 to 1 pound per acre; and toxaphene - 1 to 

 1.5 pounds per acre as used in these programs to control grasshoppers, and as 

 used (in bait at about l/lO the dosage) to control Mormon crickets [llj. 

 Although the dosage rates are low, the full impact of the toxicant is felt as 

 there is little filtering effect of higher strata of vegetation such as occurs 

 in forests during aerial application. 



Furthermore, under conditions of operational spraying of grasshopper- 

 infested croplands and rangeland, Bureau investigators have found that parts 

 of treated areas may receive as many as three overlapping doses in the same 

 season. Certain land most heavily infested with grasshoppers, such as alfalfa, 

 corn, wheat, and soil-bank land, are especially attractive habitat also for 

 pheasants. A recent study of the food habits of pheasants in South Dakota by 

 Trautman [62] revealed that grasshoppers are the most abundant kind of animal 

 matter eaten by pheasants and that young pheasants eat a much higher proportion 

 of grasshoppers than do adults. Hence young pheasants may be especially vul- 

 nerable to grasshopper control operations; as yet the Bureau does not have suf- 

 ficient data to know to what extent pheasants in the field are actually affected 

 by grasshopper insecticides. 



Aldrin in bait form has been sho¥fn to kill a few birds [l7] and up to 70^ 

 of mice present (Yeager and Sandfort, unpubl.). In marsh areas aldrin reduced 

 duck production up to 335^ (Knedel, unpubl.). Heptachlor was found to be very 

 toxic to crayfish, and chlordan treatments reduced duck production by over bO% 

 and are capable of killing large numbers of fish [ll], [42], Toxaphene treat- 

 ments are very poisonous to fish and small losses of ducks and coots have also 

 Deen reported [il], [61], 



In July, 1959, the Bureau studied the effects on wildlife of 1.5 pounds of 

 toxaphene per acre as used in control of grasshoppers on a 1600-acre plot in 

 Montana. Most specimens found dead were associated with a stockpond and an 

 intermittent stream. No fish were present, nor were any mammals found dead; 

 but 53 salamanders and frogs, 17 turtles and snakes, and 20 birds of 7 species 

 were found dead. Of these, 41 specimens were analyzed chemically; all but 1 

 dead bird contained significant amounts of toxaphene. Mortality was noted 

 within a few hours of treatment. 



Other effects noted included a loss of coordination and/or loss of equi- 

 librium, or a torpid behavior on the part of surviving turtles and frogs; but 

 turtles were wary and alert 12 days after treatment, when studies ended. 

 Turtle counts dropped from 97 before treatment to 74 one day after treatment 

 and 67 twelve days after treatment. Bird counts indicated a marked drop of 

 insectivorous species (Finley, unpubl.). 



