The mechanics of larval cat flea locomotion (Siphonaptera: Pulicidae)

Subject Editor: Karen Poh While locomotion in adult fleas has been thoroughly documented, the mechanics of larval flea movement are not well described. Efficient independent movement is essential in the larval stage, as fleas must acquire food, avoid predation, and seek out preferred environmental conditions. Herein, we use high-speed videography and scanning electron microscope imaging to investigate and describe the mechanics of larval movement in the cat flea Ctenocephalides felis (Bouché). Cat flea larvae move by extending their heads, leading with their maxillary palps, and pulling the rest of their body forward in a crawl. This locomotory behavior is used across all 3 larval instars while moving across flat and through 3-dimensional substrates, moving up to 1.14 body lengths per second. Beyond projecting from the head, we find no evidence of locomotory-specific anatomical features of the maxillary palps. More generally, this is an example of behavioral co-option of non-locomotory body parts to enable larval movement, a strategy that can be found across many insect orders.