A tussock is a small piece of grass which is much longer and thicker than the grass around it. a small thick mass of grass (Perhaps from tusk (16-19 centuries))
The body of these caterpillars is covered with hairs which form long tufts or brushes
Any of various dull-colored moths of the family Lymantriidae, the caterpillars of which have tufts of hair along the back and are often destructive to deciduous trees. Typical member of the small European and New World lepidopteran family Liparidae (formerly Lymantriidae). The large, hairy larvae of most species have hair tufts, or tussocks; many have stinging hairs. Several species, including the gypsy moth, browntail moth, satin moth, and nun moth, damage trees. The larvae feed on foliage, sometimes foraging from a silken tent or a colonial nest of webbed leaves. Larvae pupate in a cocoon attached to a tree branch or trunk. Adult females range from white to brown; some, such as the white-marked tussock moth, are wingless. See also moth