Adult females naked, usually stationary; body segmented; anal tubercles conspicuous. Antennæ of six or seven joints. Feet present. Anogenital ring inconspicuous, with fine hairs.
Male pupa enclosed in a cottony sac.
Mr. Comstock proposes (Ann. Rept. of Entom., U.S. Agric. Dept., 1881, p. 339, note) to include in this genus all the species of Eriococcus. The organic difference disclosed by the formation of a sac in that genus and the absence of a sac in Rhizococcus seems to render the separation of the two necessary.
58. Rhizococcus celmisiæ, Maskell.
N.Z. Trans., Vol. XVI., 1883, p. 135.
([Plate XVI.], Fig. 1.)
Adult female deep red in colour, elongated-oval, convex above and flattened below; length about 1/11in. The segments of the body are not very distinct. The abdomen ends in two large and conspicuous anal tubercles, each of which bears one strong and fairly long terminal seta and three other spines. The anal ring has eight hairs. Antennæ of six joints, sometimes looking like seven. Mentum doubtfully dimerous. The four digitules of the foot are long fine hairs. The tibia is a little shorter than the tarsus.[T] The trochanter bears one long hair and two short ones. A few large conical spines (spinnerets) are scattered over the body, and a row of smaller ones, like hairs with tubercular bases, runs transversely on each segment; also some circular spinnerets. At the edge of the body, all round, is a row of the large conical spines, which are set in groups of three on the posterior segments, of four or five on the median segments, and almost continuous on the head. When the insect is alive these spines are often agglutinated with cottony secretion so as to give the appearance of a short fringe. The four spiracles are somewhat large and circular.
[T] See note, above, under Eriococcus multispinus.
Adult male unknown.