REPORT OF THE SECRETARY. 123 



manently endemic in California, as it is in India among certain of the 

 native rodents. Should plague become firmly established among 

 ground squirrels or other of our rodents, there is danger that the 

 disease in a virulent form may be communicated from them to human 

 beings at any time; there is the added danger that as the distribution 

 of squirrels over a large part of California and other Western States 

 is practically continuous, the disease is likely to spread from colony 

 to colony, to other parts of the State, and even to other States. Thus 

 the plague epidemic in California, which at first sight might appear 

 to be of purely local concern, assumes national importance and the 

 destruction of ground squirrels becomes imperative. It is hence very 

 important to exterminate the animals in the sections immediately 

 contiguous to San Francisco, and by due care and vigilance to prevent 

 their reentry into the freed territory. A neutral belt thus being 

 established around San Francisco, and if necessary other seaports, 

 and the agency of ground squirrels in the spread of plague being 

 eliminated, should the disease at any future time enter San Francisco 

 or any other of our west coast ports it can be restricted to very narrow 

 limits, when its eradication will be comparatively easy. 



With a view to a war against ground squirrels, investigations have 

 been made during the year for the purpose of ascertaining the cheap- 

 est and most effective methods of killing them. Numerous experi- 

 ments have been made with poisons and with baits for use in different 

 localities and at different times of the year, and excellent results have 

 been obtained. 



After many experiments covering the dry season, whole barley has 

 been found to be the best vehicle for carrying the strychnine, wliich, 

 all things considered, has proved to be the most effective poison. The 

 barley is coated with a starch solution holding strychnine in suspen- 

 sion. It has been demonstrated that by a single treatment the ground 

 squirrels have been practically exterminated over large areas of wheat 

 land at a cost less than one-half that of the methods that have 

 hitherto been employed. Thus, during the past season careful tests 

 of the starch-barley preparation over 50,000 acres in several localities 

 in the State proved that ground squirrels can be practically extermin- 

 ated over large areas at a cost of from 2^ to 6 cents per acre, depending 

 on the abundance of the squirrels and other local conditions. The 

 method has been tested widely enough to prove that during the dry 

 season, from April till October 15, it can be successfully used in all 

 parts of the State, and it works equally well on the three species of 

 ground squirrels found there. The starch-barley preparation has 

 the added advantage that it destroys practically no wild birds and 

 may be safely employed in pastures, on sheep ranges, and along 

 public highways. 



