This conspicuous insect is chiefly mentioned on account of a very curious habit possessed by the females of congregating in large numbers on matai trees, as many as fifty or sixty specimens being often found huddled together under a single flake of the bark. The males are occasionally taken flying in the open, but I have never seen any amongst these large assemblages of females. Whether the {39}ichneumons are parasitic on some insect which lives on the matai, or whether they assemble to feast on the sweet juice occasionally exuded from its bark, it is impossible to say, but in either case the complete absence of males is a very remarkable circumstance. Family ICHNEUMONIDÆ. _Scolobates varipes_ (Plate III., fig. 8). The larva of this little insect is parasitic on the useful larva of _Syrphus ortas_ whose life-history is recorded on page 57. It is very common in some instances, and must consequently destroy a considerable number. It entirely eats the soft portions of the insect, and may afterwards be found lying snugly within the hard empty shell of the deceased syrphus pupa, which acts as a cocoon for it while undergoing its own pupa state. The perfect insect may be often observed amongst herbage, searching for syrphus larvæ to deposit its eggs in. {40}CHAPTER V The Diptera. The next Order which comes under review is the Diptera, which includes all the two-winged insects, and constitutes a most extensive Order in respect to the number of distinct species. When, however, the numbers of individuals of the same species are considered, it is probable that this Order includes a greater proportion of the insect-world than all the others put together. The preponderance of these insects over the rest holds good with greater force in New Zealand than in many other countries, and this fact may be almost inferred from the large number of spiders present here, which are chiefly dependent on Diptera for their support. The important function of clearing away refuse matter is almost entirely performed by the members of this Order, as the Necrophagous Coleoptera and other scavengers which exist in such large numbers in many countries are practically absent here, and their work consequently devolves upon dipterous insects. Group NEMOCERA. Family CULICIDÆ. _Culex iracundus_ (Plate IV., fig. 1, 1a larva, 1b pupa).