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Show 236 MR. R. SHELFORD OX MIMETIC IXSECTS AXD [Nov. 4, belonging to the most diverse orders, such as Hemiptera, Diptera, Lepidoptera, and Coleoptera. The model is one of those reddish-ochraceous Braconids, of which there are many representatives in Borneo, all being more or less common. This particular species, with a conspicuous black stigma on the fore wing, is eminently a mountain form, as the numerous specimens in the Sarawak Museum bear witness. Mt. Matang at any elevation above 1500 feet is its favourite haunt, but I have never taken it below that altitude. The mimic, which was recently described 1 by Mr. McLachlan, was captured in the month of August also on Mt. Matang, at an altitude of 2500-2800 feet. It, too, is reddish-ochraceous, whilst each wing bears a black stigma, those 011 the fore-wings being slightly more conspicuous than those on the hind-wings ; the sides and ventral surface of the abdomen are pure white (in the fresh condition), so that when the insect is seen in profile its somewhat bulky body appears to be reduced approximately to the size of the body of its model ; as, further, the model also has the ventral surface of the abdomen coloured white, the resemblance between the two insects is still greater (compare Plate X IX . figs. 22 & 23). This method of producing a thin-bodied or wasp-waisted effect by white patches is by no means uncommon amongst insects; I shall be able to give further examples of it in this paper (vide infra, pp. 238, 241), and at present need only refer to the well-known Soudanese Locustid Myrmecophava fallax (Br.) mimicking an ant, and to the Moth Pseudosphex hyalina which mimics a Sphex. ii. Mimic. Mantispa sp. Plate XIX. fig. 27. Model. Polistes sagittarius (Sauss.). Plate X IX . fig. 26. The Wasp, P. sagittarius, is an extremely common species and is rendered highly conspicuous by reason of a red band on the second abdominal segment; the rest of the body is black, varied on the head and thorax with a rich red-brown; the wings are fuscous, becoming flavo-hyaline outwardly. The mimic is black with the second and third abdominal segments red, the width of these two segments closely corresponding with the large second abdominal segment of the wasp; the wings are hyaline, but largely shaded with fuscous at the base and along the costal margins and flavo-hyaline at the apex (compare figs. 26 & 27). A closely allied species from Assam is in the Hope Collection at Oxford, with the MS. name of M. nodosa (Westw.). The specimen belonged to the Cantor Collection. iii. Mimic. Mantispa sp. Plate X IX . fig. 25. Model. Polistes sp. near diabolicus (Sauss.). Plate X IX . fig. 24. The general colour of the Wasp is reddish-brown, the abdomen is covered with a fine silky pubescence golden in colour; this 1 Ent. Month. Mag. (ser. 2) vol. xi. 1900, pp. 127-128. |