1936] MAMMALS OF OREGON 381 



vicinity. Goldman reported them as then rarely seen and probably 

 mostly already hibernating. Another collected by Preble at Fort 

 Klamath on September 14, 1896, gives the latest record for the 

 State. Another bat reported by Stanley G. Jewett at Miller's, near 

 the mouth of the Deschutes Kiver, on April 14, 1915, and thought to be 

 this species would give the earliest record for appearance in spring 

 if correctly determined. These records would indicate about 7 

 months of hibernation which probably explains the 10-month period 

 of gestation, extending approximately from the middle of August 

 to the middle of June in this species. 



Food habits. These big brown bats are hearty feeders with large 

 stomachs, but little is known of their actual food supply. The 

 stomach contents indicate a wide range of species of insects, but few 

 of the species have been carefully determined. At Vida they were 

 feeding high in the air mostly beyond the range of the heaviest loads 

 of fine shot, and the few secured seemed to be filled up with some 

 kind of high-ftying beetle. One of the bats had a small striped beetle 

 in its mouth when it struck the ground, but this was lost. 



At the Arnold Ice Caves, 14 miles southeast of Bend, the brown 

 bats were common, flying out and in the mouth of one of the large 

 cave openings, and zigzagging back and forth under the broad arch- 

 way of the entrance. Often they would alight on some point of the 

 roof and sit for a moment eating their insect prey, and under these 

 feeding spots the ground was strewn with wings of moths, beetles, 

 and flies. A few of the wings saved and referred to the Bureau of 

 Entomology and identified by H. E. Dyer represented several species 

 in the genera Euoxia and Cucullia of the Noctuid moths and others 

 in the genera Nemora and Stomnodes of the Geometrid moths. The 

 species could not be determined from so scant material. The wings 

 of a crane fly (Tipulidae) were also identified. 



Economic status. During the greater part of the months of insect 

 activity these bats are found in greatest abundance among the forest 

 trees where they glean their insect food and probably serve as an im- 

 portant factor in the protection of our forests. The specific insects 

 eaten are not well known, but the stomach contents of the bats show 

 a large proportion of moth and beetle remains, and these would pre- 

 sumably include serious enemies of the trees. Until a more detailed 

 study of bats is made it will not be known how much is owed to these 

 useful workers of the night. 



LASIONYCTERIS NOCTIVAGANS (LE CONTE) 

 SILVER-HAIRED BAT 



V[espertilio] noctivagans Le Conte, McMurtrie's Cuvier, Animal Kingdom, 

 v. 1, p. 431, 1831. 



Type locality. Eastern United States. 



General characters. Size medium, spread of wings about 12 inches, ears 

 short and wide (pi. 52, A); tragns short; upper surface of tail membrane 

 hairy ; fur long and soft ; general colors blackish with silvery frosting of white 

 hair tips over back and belly ; total number of teeth 36. Color of upper parts 

 clear black or brownish black with pure white tips over back; lower parts 

 black or dark brown, with a few white-tipped hairs over belly; membranes, 

 feet, ears, and nose black or blackish. 



Measurements. Spread of wings, 300 mm. Total length, 100; tail, 40; 

 hind foot, 9; forearms, 42. Weight of one small individual in spring, 8 g, but 

 the Crinuells give weights up to 10 and 12 g. 



