Different light conditions influence the activity of Eusthenia costalis Banks (Plecoptera: Eustheniidae)

Late instar nymphs of Eusthenia costalis Banks (Plecoptera: Eustheniidae) reduced the amount of time they were active outside a refuge when illuminated by a 40 W red incandescent light globe than when illuminated with infrared light emitting diodes. They were active outside the refuge nearly four times longer (54% ± 4%, N = 6; mean ± S.E. percentage of time observed active) when illuminated with infrared light than when illuminated with red light (15% ± 4%; N = 6). The type of light chosen to facilitate observation could confound analysis of the behaviour of predatory stoneflies. Eusthenia's sensitivity to light suggests that other predatory stoneflies should be assayed for sensitivity to light of different wavelengths. © 2006 Taylor & Francis.