Genus Myopsocus Hagen.
In this genus the median vein is much zigzagged in both wings. In the forewing M runs obliquely upwards to meet Rs, then bends sharply downwards, at right angles to its former course, until it reaches the top of the cubital loop, when it again bends obliquely upwards and runs to the apex, dividing into three branches. The basal piece of Rs, the middle piece of M, and the distal piece of Cu1a lie almost in one straight line crossing the wing obliquely. In the hindwing M fuses with Rs for a short distance, then leaves it almost at right angles and curves strongly round to run longitudinally to a point below the apex. The forewings of the species of this genus are more or less heavily marked with brown, grey, or fuscous.
Genotype.—Myopsocus lugens Hagen.
Two species of this genus have been described from Australia, one from New Guinea, and one from New Zealand.
Kolbe, H. J., Ueber das Genus Myopsocus und dessen Species, Ent. Nachr., ix, 1883, pp. 141–46. (M. novae-zealandiae described on p. 145, loc. Wellington.)
Psocus zelandicus Hudson, 1892, Man. N.Z. Ent., p. 107, and pl. xvi, fig. 2, 2a (larva). Myopsocus novae-zealandiae Kolbe, Hutton, 1899, Trans. N.Z. Inst., vol. 31, p. 211 (mentions that the types of this species were sent by Hutton to McLachlan in 1873).
Forewing—male, 4—4.5 mm.; female, 5—5.5 mm. Expanse of wings—male, 9—10 mm.; female, 11.5—12.5 mm.
This species has already been well described by Kolbe and Hutton. It is very much larger than any other known New Zealand Psocopteron, and can be at once recognized by the dark forewings, mottled brown or fuscous, as shown in Plate 18, figs. 5, 6. Points that should be noted are the following: The males are much smaller and darker in colour than the
females. When the forewings are fuscous the pterostigma remains brown, and so shows up very clearly, especially in the males. This brown colour really overlaps the actual pterostigmatic area, as shown in text-fig. 2, where the boundary of the brown colour is shown by the dotted line, lying outside the greatly bent posterior border of the stigma. In the forewing, vein Sc remains separate from R1, running close above it up to the base of the stigma. In the hindwing, Sc is vestigial. In the forewings of most specimens M just touches Rs at one point and the top of the cubital loop at another; occasionally one may find a specimen in which contact just fails in one or both cases, and sometimes there is fusion for a very short distance. The basal tarsal joint is very long, and carries along its inferior border a complicated comb (text-fig. 2, b) formed from about 30 closely set teeth, each tooth being of the form shown in text-fig. 2, c. The second tarsal joint is exceedingly short, the third about twice as long as the second.
Habitat.—All parts of New Zealand; frequently very common. Near Hamilton I found many colonies of the larvae, at the end of March, 1921, clustering under the dry bark of large trees of kahikatea (white-pine). They were easily reared by keeping them on pieces of bark in dry tubes closed with cotton-wool. It is very interesting to watch both larvae and imagines feeding on the dry bark by gouging it out with their maxillary chisels, which can be seen at work, projecting far beyond the mouth.
The types of this insect are probably in the McLachlan collection at Lewisham, near London, though I cannot be certain on this point. The New Zealand species is so closely allied to M. australis Br., common in many parts of Australia and Tasmania, that it is a matter of great difficulty to separate the two. M. australis is generally browner in colour, and in most specimens shows a definite fusion of M with Rs and also with the cubital loop for a short distance, in the forewing. In both species the male carries a pair of hooked terminal appendages, those of M. australis appearing to be somewhat shorter and less sharply pointed than in the New Zealand species.