MAMMALIA 249 



they girdle the trees beneath the surface of the ground their presence 

 is often not noticed until the trees begin to wither and die. They not 

 only girdle the trees but frequently cut the roots entirely through. 

 While not so prolific as the meadow mice their protected, under- 

 ground life makes up for their slower breeding. 



In destroying field mice there are three distinct lines of attack: 

 traps, poisons and clean cultivation. 



In some cases, especially on small areas, an ordinary good type of 

 mouse trap may be used to advantage. It may be baited with some 

 sort of grain or it may be set in the runways unbaited, so that the 

 mice may run over and spring it by accident. Fifteen or twenty 

 traps per acre may be used for several weeks. 



In most cases it will probably be better to use poison, especially 

 over large areas and when the mice are very numerous. Strychnine is 

 generally used and various substances are employed as bait. Lantz 

 recommends the following formulae: 



Dry Grain Formula. Mix thoroughly i ounce of powdered strychnine 

 (alkaloid), i ounce powdered bicarbonate of soda, and Y% ounce (or less) 

 of saccharine. Put the mixture in a tin pepper box and sift it gradually 

 over 50 pounds of crushed wheat or 40 pounds of crushed oats in a metal 

 tub, mixing the grain constantly so that the poison will be evenly distributed. 



" Wet Grain Formula. Dissolve i ounce of strychnia sulphate in 2 quarts 

 of boiling water. Dissolve 2 tablespoonfuls of laundry starch in ^ pint of 

 cold water. Add the starch to the strychnine solution and boil for a few 

 minutes until the starch is clear. A little saccharine may be added if desired, 

 but it is not essential. Pour the hot starch over i bushel of oats in a metal 

 tub and stir thoroughly. Let the grains stand over night to absorb the 

 poison. 



"Potato Formula. Cut sweet potatoes into pieces about as large as good- 

 sized grapes. Place them in a metal pan or tub and wet them with water. 

 Drain off the water and with a tin pepper box slowly sift over them powdered 

 strychnine (alkaloid preferred), stirring constantly so that the poison is 

 evenly distributed. An ounce of strychnine should poison a bushel of the cut 

 bait." 



Chopped alfalfa hay may also be used and has the advantage over 

 the grain bait that it does not endanger the life of birds. An ounce of 

 strychnia sulphate dissolved in 2 gallons of hot water will poison 30 

 pounds of the alfalfa if it has been moistened with water first. The 



