Walking insects probably monitor leg movements to estimate how far they travel, whereas flying insects monitor optic flow. © 2006 Elsevier Ltd. All rights reserved.
Collett, M., Collett, T. S., & Srinivasan, M. V. (2006, October 24). Insect Navigation: Measuring Travel Distance across Ground and through Air. Current Biology. https://doi.org/10.1016/j.cub.2006.09.027