KILLING WOODCHUCKS WITH CARBON BISULPHIDE 47 



with one ounce of bisulphide of carbon. Two days later at 2 

 p. in. it had not been uncovered. Still another of much the 

 same sort was treated in like manner and with like result. 



In 1901 no particular experiments were made at Durham, 

 but through the kindness of one of our students, Mr. Percy A. 

 Campbell, I am able to give the following results of some 

 work in this line done at Litchfield, N. H. Mr. Campbell's 

 report is as follows : 



'' The first day that I killed woodchucks with carbon bi- 

 sulphide was in the last of June before the grass had been cut, 

 so that tkere were a few holes which I did not find. I started 

 out with a small can of carbon bisulphide, some old cotton 

 in my pocket, a handle basket, and a shovel. I began on one 

 side of the field and treated every hole that I came to. I first 

 filled the basket with dirt and set it above the hole ready to 

 turn in ; then taking a small piece of cotton which I could hold 

 easily between my thumb and finger I poured upon it just 

 enough carbon bisulphide to saturate it. Then I threw this 

 into the hole as far as possible and immediately poured in the 

 dirt and filled the hole up even with the surface. If there was 

 more than one entrance to the burrow I alwavs filled in all but 

 one before the treatment. Several holes were in the river bank 

 and some in the grass land. In each of three cases I saw 

 woodchucks go into the burrow just before I treated it ; none 

 of these was dug open afterward. Out of about twenty-five 

 burrows that I treated that afternoon, all of which gave evi- 

 dence of having been recently used by woodchucks, only two or 

 three were dug open and these apparently had been burrowed 

 into ft'om the outside rather than opened from the inside, as 

 the earth was thrown back awav from the holes. 



" After the grass was cut I followed up this treatment as 

 fast as untreated holes were found, with the result that by the 

 latter part of August hardly an open burrow could be found 

 upon the farm and it was very seldom that a woodchuck was 

 seen. 



'' One day I found a burrow with two woodchucks in it. 

 Filling up one of the outlets I put the bisulphide in the other 

 with the result that the holes were never reopened. 



'* On another farm a short distance from home I treated 



