They make erratic leaps when disturbed

• Wingless insect living in dark moist places as under dead tree trunks

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
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.

Wiktionary Word definitions in Wiktionary
n. A wingless insect which can jump large distances when disturbed, in the Machilidae family.

WordNet Word definitions in WordNet
n. wingless insect living in dark moist places as under dead tree trunks; they make erratic leaps when disturbed [syn: jumping bristletail ]