Differs from the European _R. gnidii_ in size, colour, and habitat, that species living on the roots of grass, while the New Zealand insect is arboreal. There are also differences in the foot and in the arrangement of the spines and hairs. It is possible that this insect may, in its latest stage, construct a sac: in that case, it would belong to _Eriococcus_. 59. Rhizococcus fossor, Maskell. N.Z. Trans., Vol. XVI., 1883, p. 136. (Plate XVI., Fig. 2.) Female naked in all stages, but the adult usually buried in a pit. Male pupa enclosed in a white, elongated, cottony sac, which is about 1/20in. long. Adult female greenish-yellow in colour, sometimes brown, stationary; sometimes resting on the leaf, usually partly enclosed in a circular pit; almost circular in outline, flat beneath and slightly convex above; length, about 1/15in. In the last stage, after gestation, it becomes dark-brown. The cephalic part is smooth; the remainder segmented. The abdomen ends in two very small anal tubercles, which are nevertheless somewhat conspicuous on account of their brown colour. Between them there protrudes a long thick pencil of white cotton. Antennæ short, with six joints, the last joint bearing several long hairs. Feet very small; the femur rather thick; the tibia is shorter than the tarsus by about one-third; the four digitules are long fine hairs. The anal tubercles have not terminal setæ; anal ring inconspicuous. A row of a few conical spines, set far apart, runs round the edge of the body, but none elsewhere, nor any circular spinnerets. There is no sign of a sac in any stage. Female of the second stage oval, flatter than the adult, and of a rich golden colour; length, about 1/40in. The segments of the body are somewhat more distinct than in the adult. The anal tubercles are proportionately larger, and bear terminal setæ. Antennæ longer than in the adult, with six joints. Feet also longer. All round the edge runs a row of conical spines, set more closely than in the adult; and from each of these springs a long curly tube of white cotton, making a kind of fringe to the body; each tube is a little dilated at the end, and then tapers to a narrow point. The base of each conical spine is a somewhat large tubercle. Young larva free, active, elongated, slightly convex, tapering to the anal extremity; colour yellow; length, about 1/60in. Antennæ as in adult, with six joints. Feet somewhat large. Anal tubercles thick, conspicuous, setiferous, with one short hair. On the edge of the body a row of conical spines set far apart, and on the dorsum four other longitudinal rows. Adult male red in colour, about 1/30in. long. Antennæ of nine joints, all bearing hairs; the last joint nearly globular. Feet slender; digitules fine hairs. Abdominal spike short, thick, with sometimes a curved appendage. A rather strong seta on each side of the base of the spike.