96 RODENTS OP IOWA 



being damaged. In addition, nurseries and orchards are often 

 attacked and serious loss thereby sustained. 



In general, the methods of control recommended for the meadow 

 mouse will serve for the present form. Wheat, corn, oatmeal, or 

 the seeds of sunflower, tomato or pumpkin, poisoned with the 

 strychnia sulphate solution offer the best means of combating this 

 vole where it has become a pest. In placing the poisoned baits it 

 is a good plan to distribute them in the underground tunnels 

 where the voles are most likely to find them and where the lives 

 of birds and other animals will not be endangered. 



Guillotine traps, baited or not, may be set in the underground 

 tunnels across the runway after a place has been enlarged suffi- 

 ciently to receive the trap. The opening to the outside should 

 then be closed. This method is effective for small areas such as 

 lawns and gardens. 



It cannot be too strongly urged that clean and thorough culti- 

 vation, particularly of nurseries and orchards, the elimination of 

 brush, dead grass and debris which offers the animals hiding 

 places, the protection of natural enemies, and the proper and 

 periodic rotation of crops, are all preventive measures which if 

 properly carried out will eliminate likelihood of infestation by this 

 vole. A high state of cultivation materially lessens danger from 

 attack. 



COMMON MUSKRAT. MUSKRAT. 



Fiber zibethi-cus zibethicus (Linnaeus). 



[Castor] zibethicm Linnaeus, Syst. Nat., XII ed., I, 79, 1766. 



Description. Color above dark chestnut brown, darkest on 

 head; fur of back and rump mixed with long, blackish brown 

 hairs ; sides chestnut ; feet dark brown, the claws yellowish brown ; 

 tail black, sparsely haired, compressed vertically; color below 

 brownish white, a little lighter on throat and belly; underfur light 

 grayish ; a small spot on chin and hair of wrist and heel blackish. 



Measurements. Total length, 22.00 inches; tail vertebra, 11.00 

 inches ; hind foot,. 3.50 inches. 



Considerable variation in size and color is exhibited in this 

 form. The worn pelage is paler and duller than is indicated in the 

 above description; almost totally black specimens are occasion- 

 ally met with ; while white or partly white specimens are some- 

 times captured. Charles B. Cory in discussing this point says: 

 ''About three years ago Mr. "W. S. McCrea of Chicago, called my 



