([Plate XV.], Fig. 1.)
Sac of adult female yellow, felted, elongated-oval. Length, about 1/20in. Abdominal extremity open.
Sac of male similar to that of the female.
Adult female pinkish in colour, elongated-oval, convex, filling the sac, shrivelling at gestation; segmented, segments not conspicuous. Length, about 1/25in. Anal tubercles brownish, conspicuous, setiferous. Anogenital ring small, with eight fine hairs, which are often glued together by cottony secretion, forming a pencil between the tubercles. Antennæ of six joints. Feet having the tibia shorter than the tarsus;[S] digitules fine hairs. On the dorsal surface are a great number of conical spines, of which the largest are arranged in six longitudinal rows; from the spines sometimes protrude some cottony tubes with an expansion a little below the tip.
[S] As a rule, a tibia shorter than the tarsus characterizes an insect not yet arrived at the adult stage. The genera Eriococcus and Rhizococcus sometimes present exceptions to this rule. See also, above, the genus Eriochiton.
Young larva free, active, elongated-oval, flattish; spines as in adult.
Adult male orange-red in colour; length, about 1/25in. Antennæ of ten joints. Abdominal spike short, thick, with a curved appendage. Feet normal.
Habitat—On Rubus australis, Riccarton Bush, Canterbury; on Knightia excelsa, Cyathodes acerosa, Wellington.
The very numerous conical spines distinguish this species from that known as Acanthococcus aceris, Signoret, the European species.
There seems to be no sufficient reason why the genus Acanthococcus should have been separated from Eriococcus, and they have been here reunited. The only difference mentioned by Signoret is the colour and texture of the sac, an unimportant character in this case.