8 
THE CALIFORNIA GROUND SQUIRREL. 
squirrels has now spread over so large an area that it will be very diffi- 
cult to wipe it out. The limits of the area are not known, but in the" 
fall of 1909 plague-infected stjuirrels were found near Ilollister, 50 
iniles south of San Francisco Bay, where in June of the present year 
(1910) a man died of the disease. 
On the south, infected squirrels have been discovered by the Pubhc 
Health and Marine-Hospital Service near Watson^dlle, a few miles 
back of Monterey Bay : near King City in Salinas Valle}', and near 
Tres Pinos and Paicines in San Benito Valley. On the east the}^ 
have been found near Lathrop and San Joaquin City in San Joaquin 
County ; near Gustine (8 miles south) and Ingomar (8 miles west) in 
Merced County ; and near Crows Landing (6 miles west and 11 miles 
southwest) in Stanislaus County. 
MEANS OF DESTRUCTION. 
Among the means of destruction not to be lost sight of is the 
encouragement of the squirrel's natural enemies — especially co^'Otes, 
badgers, foxes, bobcats, and the golden eagle. 
Ground squirrels may be shot, trapped, or poisoned, or they may 
be killed by certain gases forced into their burrows — notably fumes 
of bisulphid of carbon and burning sulphur. 
TRAPPING. 
Various traps have been used with success. The ordinary No. 0 
steel trap placed unbaited in the mouths of the burrows sometimes 
yields excellent results, but the best and most humane trap in use at 
the present time is the so-called guillotine trap — a trap wliich kiUs 
the animal instantly by striking it a heav;\' blow on the back of the 
neck. Any food attractive to the squirrels may be used for bait; 
grain, rolled oats, dried prunes, and pieces of sugar beet have proved 
successful. 
POISOXIXG. 
In places where ground squirrels are abundant over considerable 
areas the simplest, most effective, and least expensive way to destroy 
them is by the use of gi^ain poisoned with, stryclmine. 
Phosphorus and cyanide of potassium, owing to the great danger 
attending their use, are not recommended, especially since they are 
not more effective than strychnine. 
In poisoning -snth str^xlmine, the grain recommended for bait is 
barley. Compared with wheat, it is usually more attractive to the 
squirrels and is far less hkely to be eaten by birds. 
There are two distinct methods of preparing the poisoned grain: 
(1) By soaking or boiling in the poison solution; (2) by coating with 
the poison solution. The Biological Survey, in extensive experiments 
in various parts of Cahfornia conducted by S. E. Piper, has found that 
