EFFECTS OF DDT AND OTHER INSECTICIDES 



populations, the importance of the 

 wholesale decline of food organ- 

 isms could not be determined on 

 the basis of the single season of 

 study. 



TETON NATIONAL FOREST. WYO. 



During July and August 1947, 

 the Bureau of Entomology and 

 Plant Quarantine, in cooperation 

 with the Forest Service, both of 

 the United States Department of 

 Agriculture, made an experimen- 

 tal attempt to control the moun- 

 tain pine beetle in the Teton Na- 

 tional Forest, Wyo. Four plots, 

 totaling 480 acres, were treated. 

 On three of these (288 acres) , the 

 dosage applied was 5 pounds of 

 DDT to an acre, and on the fourth 

 (192 acres) the dosage was 7i4 

 pounds of DDT to an acre. In 

 each case two treatments, using 

 one-half the total quantity for 

 each, were made with an 8-day 

 interval between them. A care- 

 ful check of results showed that 

 control of this pine beetle was not 

 gained. The lack of success was 

 attributed chiefly to the inade- 

 quate deposit of DDT on the boles 

 of the trees by aerial application. 



Studies of the effects on wild- 

 life of this control attempt were 

 made by members of the Fish and 

 Wildlife Service and of the Bu- 

 reau of Entomology and Plant 

 Quarantine. 



Mammals 



Plots for studying the effect on 

 small mammals were selected, one 

 in an area that received an appli- 

 cation of 5 pounds of DDT to an 



acre, one in an area that received 

 an application of 7yo pounds to an 

 acre, and another in an untreated 

 check area. In all of these an 

 index to the population level was 

 obtained by live-trapping both be- 

 fore and after each of the two 

 applications. The methods and 

 intensity of the study were such 

 that only marked population 

 changes were likely to be noted. 

 From the trapping returns 

 there was no indication of a 

 marked effect on any of the fol- 

 lowing species : red-backed mouse 

 (Clethrionomys gapperi satura- 

 tus) , field mouse (Microtus lon- 

 gicaudus) , white-footed mouse 

 (Peromyscus maniculatiis artemi- 

 siae) , jumping mouse (Zapus 

 princeps princeps) , chipmunk 

 (Eutamias amoenus luteiven- 

 tris) , and pine squirrel (Tamia- 

 sciunis douglasii). There were 

 some indications from field obser- 

 vations, however, that the heavy 

 dosages may have caused abnor- 

 mal behavior and possible mor- 

 tality. On August 31, the day fol- 

 lowing the second application on 

 one of the areas treated with a 

 dosage of 5 pounds to an acre, 

 Stanley Rhoades, of the United 

 States Forest Service, reported an 

 unusual condition among trapped 

 chipmunks. Practically all ani- 

 mals handled at that time were 

 alternately sluggish and in a state 

 of muscular tremors. Similar 

 symptoms were noted in at least 

 one free chipmunk, which would 

 indicate that confinement was not 

 the cause of the atypical condition 

 noted among trapped individuals. 



