The eastern pipistrelle is Wisconsin's smallest bat, and weigh s just four to eight grams (0.1-0.3 oz; Kurta 1995). This species has a forearm length of 32-36 mm (1.3-1.4 in) and a total length of seven to eight centimeters (2.8-3.1 in; Kurta 1995). Total wingspread is 21-26 cm (8.3-10.2 in; Barbour and Davis 1969). Fur color ranges from golden brown to reddish brown. The eastern pipistrelle has black forearms that contrast with the red membrane of the wing. The dorsal guard hairs have a distinct tricolored appearance - dark at base, yellowish in middle and dark at the tip - that give the bat a harlequin appearance.
Eastern Pipistrelle (Perimyotis subflavus) Species Guidance
Wisconsin Department of Natural Resources (2013). Eastern Pipistrelle (Perimyotis subflavus) Species Guidance. pp 10.