Millipedes, like insects have a single pair of antennae on the head. The antennae can be tucked away when the millipede is curled in a defensive position or extended to the front and sides to receive sensory information when the millipede is in motion. The antennae of the millipede support several types of sensory hairs that respond to chemicals or mechanical deformation. They can detect chemicals on surfaces and airborne odors. Mechanoreceptors respond to wind and air currents and to tactile stimuli when the antennae contact surfaces.
Compared to insects such as crickets that use their antennae for navigation by touch in the dark of night, the antennae of millipedes are much shorter in relation to body length. Thus, they are better adapted for sense of smell than use as “feelers”. It is not clear what odors are important to their survival. Millipedes do not exhibit a strong response to most odors. What do millipedes smell and how do they react? That can only be known by further study.
*Kyung‐Hwun Chung & Myung‐Jin Moon. Antennal sensory organs in the female millipede Orthomorphella pekuensis. Integrative Biosciences 10:183-189.