102 



"To determine more accurately the quantity of mice and other 

 foods eaten by the shrew, experiments were made in the laboratory. 

 A shrew was kept in confinement for over five weeks, in a wire cov- 

 ered cage in which earth was placed to a depth of about. 10 cm. When 

 practicable, live food was furnished. Among the various foods tried 

 were meadow voles and house mice (Mus musculus), May beetles 

 (Lachnosterna) and their grubs, moth . larvae, other insects 

 and pupae, earthworms, snails, sowbugs, carrots, crackers, 

 roots of grasses and other plants. None of the last three 

 articles were ever touched as food. ****** other in- 

 sects such as various ground beetles, giant water bugs (Benacus), 

 and HydropMlus triangularis, were furnished. All were eaten, but 

 the ground beetles were the favorite. Other larvae of insects besides 

 Lachnosterna were readily taken, even the "woolly bear of Pyrrharctia 

 isabella.. Sowbugs were eagerly devoured. When live food was not 

 to be had, beef was furnished, and was eaten readily. I made only 

 two stomach examinations. One stomach contained an insect larva 

 mutilated beyond recognition; the other the remains of a meadow vole, 

 recognizable by the hairs swallowed with the flesh. Vegetable foods 

 were invariably rejected, though Professor Reighard has captured the 

 shrew in traps baited with nut meats scented with anise oil, and the 

 specimens taken still had fragments of the nut meats in their teeth. 



* * * * Too little ^ heretofore been known of the short- 

 tailed shrew to make an estimate of its econmoic importance practic- 

 able. Stomach examinations 'are almost wanting, my own work includ- 

 ing but two. However, from data concerning the quantities of food in 

 laboratory and field, I have attempted an estimate of the economic 

 importance of Blarina. * * * * p r example one month's rations 

 of voles alone would be 20; of house mice 30; of adult May beetles, 

 450; and so on. 



" * * * * *Estimating the number of shrews as I have done 

 at four per acre, it appears the number of meadow voles devoured by 

 them on a farm of 100 acres in a year is 100x4x12x8=38400. Since 

 this number can scarcely be supplied, the capacity of the shrews for 

 keeping the voles in check is not strained. Where this quantity of 

 voles can not be found, either other foods must be eaten in equivalent 

 amounts, or the shrew is capable of subsisting on shorter rations or 

 the estimated four shrews per acre can not exist. Farmers should 

 take note of the economic value of Blarina. In their zeal to rid their 

 premises of noxious animals, they sometimes kill indiscriminately 

 anything that looks like a mouse. One of these animals evidently 

 kills many more voles in a year than the farmer himself. 



