Light dependent shift in the anti-predator response of a pyralid moth

Male small china-mark moth Cataclysta lemnata (Pyralidae) swarming over shallow water show a flight activity that peaks during the afternoon but which sometimes is extended into the night. We exposed wild, naturally flying C. lemnata to simulated predator attacks consisting of a) bursts of ultrasound (26 kHz, simulating a bat) and b) a thrown stick (rapid movement, simulating a small bird), during day and night, respectively. We thus investigated the possibility that these moths are able to switch between defensive strategies as the predator regime shifts from insectivorous birds to bats in the evening. The defensive response differed qualitatively between day and night, as expected, but it was independent of the kind of stimulus. We thus demonstrate a previously unknown flexibility in the defensive strategy of moths.