THE MONTHLY BULLETIN. 365 



POISONING GROUND SQUIRRELS. 



By W. L. Burnett, Deputy Pest Inspector. Fort Collins, Colorado. 



For the past four or five years, the state of Colorado, through the office of the 

 Slate Entomologist, has been carrying on extensive experiments to secure the best 

 and cheapest methods for the control of ground squirrels, prairie dogs, and other 

 rodents destructive to agricultural crops. 



In these efforts we have been very successful. The Wyoming ground squirrel 

 (CiUllus elegant) that inhabits the northwestern counties of the state, has been 

 our hardest problem. It would take poison very readily in early spring when il 

 first came out of hibernation, but after green food became abundant it would not eat 

 the poison to any great extent. The writer, knowing this to be a serious drawback 

 to the successful control of this pest, spent the greater part of two seasons during 

 the period of activity of the squirrels, experimenting with poisons, and combinations 

 of poisons, to overcome this difficulty. After two seasons trial, we are satisfied that 

 in Formula No. 28, as given below, we have a formula that can be used snccessfully 

 at any season of the year when the squirrels are active, no matter how abundant the 

 green food. 



In California the two species of ground squirrels most destructive to agricultural 

 crops, are the California ground squirrel (.Citellus bceeheyi), and the Douglas 

 ground squirrel {Citellus douglasi), both of which are larger and have longer tails 

 than Citellus elegant. 



The food habits of the three species are very similar, the greatest difference being 

 that the two California species do serious damage to fruits and nuts, while in 

 Colorado neither fruit nor nuts arc raised in the section infested with Wyoming 

 ground squirrels. 



The two California species are active the year around, except in the mountain 

 portions, while the Wyoming ground squirrel's season of activity is only about five 

 months in the year, and the most difficult months to successfully use poison have 

 been July and August, while with the California ground squirrel the difficult 

 months are December and January. 



As December and January are in what is known as the rainy season in Cali- 

 fornia, the gelatine-coated grain should have a decided advantage over all others, 

 as it will stand more moisture and still be effective. 



We are not making any statement as to what can be done with this formula for 

 the control of the California ground squirrels, as it may be a complete failure — we 

 only know what has been done with the Wyoming ground squirrel in Colorado. 



The writer is fully aware of the fact that the poison which will successfully control 

 one species of ground squirrel may fail with others, and is also strongly of the 

 opinion that different environments may mean success or failure, even with the same 

 species. 



Colorado Formula No. 28. 

 Part 1. 



Oats 14 Quarts 



Strvi'M , alkaloid powdered — 1 ounce 



Starch J pint 



Water --- l t ua - vt 



Part 2. 



Knox gelatine. No. 1 plain (2 envelopes) 1 box 



Baking soda * ounc * 



Dark brown sugar i pound 



-Water ' " ,,:irt 



Directions. Treat grain first with Part 1. as follows: Dissolve the strychnine 

 in the quart of water; add the starch and stir until it is all dissolved ; put over fire 

 and heat until starch begins to thicken, stirring constantly. 



Pour the poisoned solution over the grain; thoroughly mix, until each grain is 

 evenly coated ; let stand for five or six hours. 



Re-treat poisoned grain with Part 2, as follows : Dissolve gelatine in warm water 

 (not boiling), add soda and stir until it stops foaming, then add sugar and when 

 dissolved pour over the poisoned grain and again mix thoroughly ; spread and dry. 



