A movable chevaux de frise of sticks

Alpheus Spring Packard, Half Hours with Insects, Boston, Estes and Lauriat, 1881, p. 132.

Cases of protective mimicry are afforded by the Caddis flies (Fig. 92), which move over the bottom, carrying about with them a movable chevaux de frise of sticks, behind which lurk a nimble pair of jaws ; or they mime innocent sticks, or build their cases of bits of moss and move about bearing as it were, subaqueous Birnam forests ; or when their tubes re built of sand imitate the irregularities of the bottom over they creep, and thus living in ambush amm the while, are protected in they turn by these disguises.