13 



eat them. In Dr. Fisher's study of the contents of 2645 stomachs of 

 birds of prey, moles were found only four or five times. ("Hawks 

 and Owls of the United States".) There seems to be a considerable 

 local variation in the numbers of moles from year to year, and they 

 are often found lying dead, but unmutilated, above ground in con- 

 siderable numbers. Many of them are badly infested with intestinal 

 parasites, which possibly tend to reduce their numbers. Two such 

 parasites, specimens of Filar ia and Spiroptera, were abundant in the 

 stomach and intestines of many of the moles collected by us for a 

 study of their food. 



My own attempts to poison moles have had uncertain success, as 

 it was difficult to tell, even approximately, the number killed. They 

 eat bits of raw beef readily in captivity, and might be poisoned by 

 putting strychnine on bits of meat and placing these in their runs. I 

 have found trapping the best way to destroy them. A sing'le mole 

 will do a surprising amount of burrowing in a week, and the number 

 of moles doing noticeable damag"e in any locality is generally not 

 large. It is difficult to tiap them in midsummer, when they frecpient 

 only their deeper burrows, but easy in spring or autumn, when they 

 work near the surface. There are a number of good mole-traps on 

 the market, all made with reference to the mole's habit of persistently 

 repairing a burrow if its roof is broken in. Where the work of the 

 mole is evidently recent, a virtual extermination by trapping is neither 

 difficult nor tedious. Even in places where they have been long es- 

 tablished, and where the ground may not be plowed up, persistent 

 work during the spring months will accomplish much. Where there 

 is an intricate network of old runs it is very difficult to trap them; 

 yet even here occupied runs may sometimes be detected. If the trap 

 is undisturbed for twenty-four hours it may be safely inferred that 

 it has been placed on an abandoned runway, and another trial must 

 be made elsewhere. During the season of 1908 experiments were 

 made by treating seed-corn with kerosene, carbolic acid, fonnalin, oil 

 of lemon, and other vegetal)le oils, to see whether moles w^ould be so 

 repelled by these substances that they would not disturb the corn. 

 No definite results were obtained, however, except where an amount 

 of repellent was used sufficient to injure the seed. 



October, 1910. 



