Thrips are small hemimetabolic insects with a distinctive cigar-shaped body plan. They are elongated with transversely constricted bodies. They range in size from in length for the larger predatory thrips, but most thrips are about 1 mm in length. Flight-capable thrips have two similar, strap-like pairs of wings with a fringe of bristles. The wings are folded back over the body at rest. Their legs usually end in two tarsal segments with a bladder-like structure known as an "arolium" at the pretarsus. This structure can be by means of hemolymph pressure, enabling the insect to walk on vertical surfaces. They have compound eyes consisting of a small number of ommatidia and three ocelli or simple eyes on the head.