The Genus _Orcus_ contains a number of metallic blue-black lady-birds which feed chiefly upon scale insects; their larvae are grey and black creatures with the dorsal surface covered with fine spines; several species are common on scale infested citrus trees. _Orcus chalybeus_, measuring about ⅛ of an inch in length, is of a uniform deep metallic steel blue. _O. australasiae_ is a larger species with two rounded yellow spots on each side of the elytra. _O. bilunulatus_ is a still larger insect, with only one yellow blotch on either side of the front of the thorax. [Illustration: =Fig. 105.=--_Orcus chalybeus_ (Boisd.). The Steel-blue Lady-bird. (“Agricultural Gazette,” N.S.W.)] [Illustration: =Fig. 106.=--_Orcus australasiae_ (Boisd.). The Six-spot Blue Lady-bird. (“Agricultural Gazette,” N.S.W.)] _Novius cardinalis_ is a tiny red and black lady-bird, very variable in its black colouration; it was better known as _Vedalia cardinalis_, when it was collected in great numbers and forwarded to America to destroy the Fluted or Cottony-cushion Scale (_Icerya purchasi_), which had been introduced from this country into California and damaged the orange trees. It has since been introduced into other parts of the world, and is now cosmopolitan. The Genus _Rhizobius_ contains a number of small black beetles finely punctured and clothed with pubescence, that gives them a rusty tint. _Rhizobius ventralis_ is very common in the bush upon young eucalypts that are infested with _Eriococcus coriaceous_; it measures about ⅙ of an inch in length and is very pubescent. _Cryptolæmus montrouzieri_, a great foe to all kinds of mealy bugs, has been introduced into Hawaii with good results. The larvae are flattened brown insects that cover themselves with short white overlapping filaments, so that their identity is quite lost; they frequently swarm in thousands upon the trunks of scale infested Auracaria pines, pupating in such numbers that they form large white patches over the tree stems. The beetle is ¼ of an inch in length; is of a uniform black tint, with the head, thorax and tip of the elytra light yellow. The Genus _Scymnus_ contains many of our smallest species: _Scymnus vagans_ is a minute black beetle only ¹⁄₂₄ of an inch in length, which can be found on mite infested foliage. _S. notiscens_, more than twice the size, is common both on wattles and orange trees; it can be easily identified by the distinct reddish blotch in the centre of each wing cover. Order VI.--LEPIDOPTERA. Butterflies and Moths.