ROD E N T I A 253 



be added an unknown amount of expense in fighting the rodents by 

 various methods, and of preventing damage by them. 



Silver listed seventeen kinds of rodents as potential enemies of 

 fruit and shade trees, especially young trees, of which five may be 

 considered serious; an experimental plot was damaged to the extent 

 of 70 per cent in 3 days by chipmunks and deer mice ; wood rats on a 

 i/5-acre tract killed 23 per cent of the pines and did more or less dam- 

 age to 34 per cent more; rabbits killed 12,000 catalpa trees on a 25- 

 acre tract; pocket gophers destroyed 25 per cent of the young silver 

 maples and nearly all the honey locusts on one tract ; total rodent dam- 

 age -to fruit and shade trees equals several million dollars annually. 25 

 Five of the eight rodent families inhabiting Kansas are distinctly in- 

 jurious; mice girdled 5000 trees in one locality. 26 Rabbits girdled 

 3000 fruit trees in one small Iowa nursery in one winter and 2000 out 

 of 4000 apple trees in Maryland in two months. 27 Other data concern- 

 ing rodent damage may be found in subsequent pages, especially under 

 rats, mice, squirrels and rabbits. 



Because of the enormous amount of damage done by rodents, the 

 United States Department of Agriculture and other organizations have 

 devoted a great deal of attention to methods of combating and suppress- 

 ing them and of preventing damage by them. Directions for the use of 

 poisons, trapping and "building them out" by means of rodent-proof 

 construction of buildings are included in many publications. 28 Aside 

 from poisoning and trapping, under some circumstances, where no 

 foodstuff is exposed to the fumes, fumigants may be used for de- 

 stroying rodents and deterrent odors for driving them out of their 

 hiding places. A great deal may be accomplished by keeping premises 

 clean and free from weed patches, rubbish heaps, brush piles and other 

 hiding and breeding places, and by preventing rodents from getting 



25 Silver, Rodent enemies of fruit and shade trees, Journ. Mammalogy, v, 165- 

 173, 1924. 



28 Sullivan, Economic value of bird life, p. 25, 1912. 



27 Beal, How birds affect the orchard, Yearbook U. S. Dept. Agric. for 1900, p. 

 299. 



28 For example: Lantz, Use of poisons for destroying noxious mammals, Year- 

 book U. S. Dept. Agric. for 1908, pp. 421-422; An economic study of field mice, 

 U. S. Biol. Surv. Bull. No. 31, 1907. Piper, Farmers' Bull., No. 352, 1909. Birdseye, 

 Farmers' Bull, No. 484, 1912. Merriam, The California ground squirrels, U. S. Biol. 

 Surv. Circular No. 76, 1910. Dearborn, Trapping on the farm, Yearbook U. S. Dept. 

 Agric. for 1919, pp. 451-484. Forbush, Rats and rat riddance, Massachusetts State 

 Board Agric., Economic Biol., Bull. No. I, pp. 38-73, 1915. Oman, Fighting the 

 pocket gopher, the prairie-dog and other rodent pests, 24th Biennial Kept. Kansas 

 Board Agric. (for 1923-24), pp. 46-60. Bruner, Pocket gophers, Univ. Nebraska 

 Agric. Exper. Sta. Press Bull., No. 29, pp. 6-7, 1908. Burnett, Report on rodent in- 

 vestigations for 1912, Office Colorado State Entomologist Circular No. 6, 1912. Hin- 

 ton, Rats and mice as enemies of mankind, Brit. Museum Nat. Hist., Econ. Series^ 

 No. 8, 1920. 



