Active aerial dispersal of minute wingless arthropods: exploitation of boundary-layer velocity gradients.

The wingless first instars of the coccid Pulvinariella mesembryanthemi exhibit active aerial dispersal behavior by standing on their hind legs. This behavior is an age-specific response to the ambient wind velocity by which the instars are able to capitalize on air velocity gradients in the thin boundary layer surrounding the host plant substrate. This dispersal tactic may be a convergent evolutionary strategy for many minute terrestrial arthropods.