38 UNIVERSITY OF COLORADO. 



other caterpillars 35%, beetles 15% (173). Aughey found 6 species of vireos 

 feeding extensively on locusts (174). 



Mniotiltidae. The wood warblers are almost exclusively insectivorous, 

 their insect food varying with the different species from 85% to 99%, 

 probably averaging 94%. They are special enemies of plant lice, scale in- 

 sects and other minute pests which are overlooked by larger birds. They 

 pass through our region in great numbers in migration, searching the bark, 

 foliage and buds for insects, and several species remain through the summer. 

 About 14 species have been investigated in some detail (175). In stomachs 

 of 6 species from a canker-infested orchard two-thirds of the contents was 

 canker worms (176). Aughey found 31 species of warblers feeding on locusts, 

 many stomachs containing from 20 to 30 locusts, and some containing over 

 40, besides other insects (177). 



Motacillidae. The pipits feed upon small mollusks, crustaceans, inset-Is 

 and seeds. They may be seen tilting and bobbing along the streams and 

 lakes at high altitudes in Colorado, where they nest, passing through the 

 lowlands in migration. In Texas they feed to some extent on cotton boll 

 weevils- (17S). Three Nebraska specimens taken in September averaged 48 

 locusts and 4 other insects each (179). 



Cinclidze. The water ouzel or dipper is one of the most interesting birds. 

 It is a common resident along the mountain streams of the west. Though 

 a passerine bird, it goes into the swift water in search of food with the ease 

 of any aquatic bird. Its food consists to a large extent of aquatic insects. 

 It is accused of catching young fish, and is often shot by fishermen for that 

 reason, but, though captive specimens have fed on small fish fry, stomachs 

 of wild specimens examined by Newstead contained no fish whatever, accord- 

 ing to McAtee (180). 



Mimidje. Mockingbirds have been accused of doing damage to fruit in 

 some places, notably Florida, Texas and New Mexico, but over most of their 

 range they are not abundant enough to do much damage (181). 



Thirty-three stomachs from Los Angeles contained an average of 23% 

 insects, and 1 nestling contained grasshoppers and crickets 92% (182). 



Two Illinois specimens contained grasshoppers and allies 60%, besides 

 other insects (183). 



Thrashers are more insectivorous than mockingbirds. Brown, thrasher, 

 121 stomachs, Maine to Florida and west to Kansas, insects and allies 63%, 

 fruit 8%, grain 3% (184). Four from a canker-infested orchard, insects 



(173) Forbes, 111. St. Lab. Nat. Hist., Bull. Vol. I, No. 6, p. 10. 



(174) Aughey, First Rept. U. S. Entom. Com., App. II, p. 27. 



(175) Beal, Agric. Yearbook for 1904, p. 254 ; U. S. Biol. Surv., Bull. No. 30, pp. 

 42-46. Judd, U. S. Biol. Surv., Bull. No. 17, pp. 103-104. 



(176) Forbes, 111. St. Lab. Nat. Hist., Bull. Vol. 1, No. 6, p. 10. 



(177) Aughey, First Rept. U. S. Entom. Com., App. II, pp. 19-24. 



(178) Howell, U. S. Biol. Surv., Bull. No. 22, p. 16; No. 25, p. 14; No. 29, pp. 

 22-23. 



(179) Aughey, First Rept. U. S. Entom. Com., App. II, p. 19. 



(180) McAtee, Proc. Acad., Nat. Sci. Phila., Vol. LXIV, p. 323, 1912. 



(181) Judd, Agric. Yearbook for 1895, pp. 415-416; U. S. Biol. Surv., Bull. No. 

 17, p. 104. Beal, U. S. Biol. Surv., Bull. No. 30, pp. 52-53. Cockerell, N. Hex. Agric. 

 Exper. Sta., Bull. No. 37, p. 53, footnote. 



(182) Beal, U. S. Biol. Surv., Bull. No. 30, pp. 52-54 



(183) Forbes, 111 St. Lab. Nat. Hist, Bull. Vol. I, No. 3, p. 142. 



(184) Judd, Agric. Yearbook for 1895, pp. 411-415 ; U. S. Biol. Surv., Bull. No. 

 17, pp. 105-106. 



