28 Entomology and Zoology Department. [Bull. 168 



whether they were eaten by the mole or by his guests, or 

 even whether the mole had a chance to accept or refuse 

 the bait before it was taken by other occupants of the bur- 

 row. The fact that a system of runways showed fresh 

 work after poison had been introduced and the baits taken 

 was, therefore, no evidence that the particular kind of 

 bait was not suitable for the purpose. A mole's system of 

 runways is so extensive that failure to retraverse or work 

 that part of it under observation during the period of the ex- 

 periment would not be positive evidence that the mole had been 

 destroyed by the poison. Since there is so much intersection 

 of burrows that it is difficult to determine the limits of each 

 individual mole's system of runways, continued activity in 

 the vicinity of a spot where poison had been put out would 

 prove nothing more than that there was at least one mole alive 

 there yet. The summary of more than a thousand records of 

 poisoning operations show that but one dead mole was found. 



In all poison experiments strychnia sulphate was used. Va- 

 rious baits were tried, with the following results and conclu- 

 sions : 



Peas. Peas were soaked for forty-eight hours in a solution 

 of one-eighth ounce of strychnia in one quart of soft hot water. 

 Seventy-eight per cent of the baits were taken, probably largely 

 by mice, as sixty per cent of the runways continued to be 

 worked by moles. This is undoubtedly an efficient bait for 

 destroying the mice that follow the mole's runways in newly 

 planted cornfields. 



Fresh meat. Small bits of beefsteak were poisoned by in- 

 serting a crystal or two of strychnia into small slits made in 

 the bait with the point of a penknife. About the same per 

 cent of baits was taken as in the case of the peas, but a few of 

 them were dug up from the surface. There is, therefore, 

 danger of poisoning such keen-scented animals as dogs and cats 

 by the use of these meat baits. Forty-two per cent of the run- 

 ways treated showed fresh work after the close of the experi- 

 ment. 



Grasshoppers. The bodies of grasshoppers were poisoned 

 in the same manner as the fresh-meat baits, the heads of the 

 insects having first been pulled off. Sixty-one*per cent of the 

 baits were taken, but forty-four per cent of the runways con- 

 tinued to be worked. 



