How bumblebees avoid collisions during flight

Vertebrates account for their body size while navigating obstacles as they move, but the ability of insects to do so is unknown. Sridhar Ravi et al. (pp. 31494–31499) observed bumblebees flying in a tunnel as the bees encountered walls containing gaps of varying width. The authors report that when bees were presented with narrow gaps, they first assessed the gap visually through side-to-side peering flights before reorienting their angle of flight to minimize their frontal profile and safely pass through the gap. In extreme cases, in which the gaps were smaller than the bees’ wingspan, bumblebees passed through the gap, flying entirely sideways. As bumblebees vary in size, the time spent assessing the gap and the reorientation performed to safely navigate it was determined not by the absolute size of the gap, but by the size of the gap relative to each bee’s own wingspan. The results suggest that flying bumblebees navigate their environment with an implicit awareness of their own body size and shape in relation to their environment. According to the authors, this ability in insects, which have much smaller brains than vertebrates, sheds light on the neural capacity needed for perception of individuals’ own body sizes. — P.G.