Img 1 A third instar cat flea larva moving by using its labrum (mouth).
Flea larvae move by contracting and relaxing their skin tube muscle. They attach themselves to the surface using their mouths. Then, once braced, bring their rear-end forward and fasten it to the surface. The mouth relaxes its hold, causing the larvae dart forward in a wriggling motion.
To move forward, a flea larva contracts and relaxes its skin tube muscle on a dry surface. Using its labrum (mouth) and nearby bristles, the larva grasps onto the surface. Once braced, it brings its posterior forward and attaches its anal struts (tail hooks) into the surface. The labrum’s hold is then released, and the larva shoots forward in a wriggling motion. Bristles covering the bodily segments also help to facilitate the movement.
Flea larvae are able to stop themselves by using their mouth parts, or, to a lesser extent, by pushing against the surface with their last body segment.
If flea larvae are disturbed or detect vibrations in their environment, they’ll coil up and flip in circles. This behavior, aided by their bristly body, causes the larvae to cling onto carpet fibers. As a result, vacuuming has limited success in removing larvae from carpets.