The Collaborative International Dictionary of English v.0.48:

machilid \mach"i*lid\, n.
   A wingless insect living in dark moist places, as under tree
   trunks; they make erratic leaps when disturbed; called also
   jumping bristletail.

   Syn: jumping bristletail.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

jumping bristletail
    n 1: wingless insect living in dark moist places as under dead
         tree trunks; they make erratic leaps when disturbed [syn:
         jumping bristletail, machilid]