CAGE SIZE AND FLIGHT SPEED OF THE TOBACCO HAWKMOTH MANDUCA-SEXTA

Flight speeds and behaviors of the sphinx moth Manduca sexta were reco rded in chambers of four different sizes (0.57, 8.5, 44 and 447 m(3)). Mean horizontal speed increased linearly with the cube root of chambe r volume from 0.57ms(-1) in the smallest chamber to 3.4ms(-1) in the l argest. The maximum horizontal speed observed was 5.3ms(-1) in the lar gest chamber. Speeds decreased linearly with the logarithm of hawkmoth proximity to the wall. In a tunnel chamber (the third largest), moths often hew in a scalloped-shaped path. At the top of the scallop, they glided for 1-5 wing beats. In the largest chamber, moths could be rec orded flying at angles other than horizontal (0 degrees). At flight an gles greater or less than 0 degrees, mean speed decreased linearly wit h angle until +/-40 degrees. At greater angles, speeds remained betwee n 1 and 2ms(-1). Moths also flew closer to the wall at flight angles d eviating from the horizontal, An allometric analysis of the flight spe eds of insects and birds suggests that M. sexta may be able to fly at 7-10ms(-1). We conclude that chamber size limits the flight speed and modifies the flight behavior of the tobacco hawkmoth.