Art. X.—Notes on a Moth-killing Spider.

By W. W. Smith, F.E.S.

[Read before the Manawatu Philosophical Society, 25th July, 1912.]

When residing at Featherston, in the Wairarapa, in November, 1907, I devoted much time to collecting a good series of specimens of all the species of hepialid moths occurring in the district. The winter and spring months of the year, though very mild, were exceptionally wet, and therefore were very favourable to the habits of the rhizophagous larvae of these large moths. The larvae of Porina umbraculata Guenée fed numerously on the roots of cocksfoot-grass (Dactylus glomerata), which fodder plant grows vigorously on the outskirts of the remnants of native forest remaining in the district. The presence of such large numbers of these larvae during these months augured well for a successful collecting season when the beautiful moths appeared on the wing. The first moth appeared at light on the 5th November; by the 11th they were numerous, and a week later we could have captured two or three dozen any night. The dwelling-house is situated in the bush, and our method of capturing these large and handsome moths without injuring them was by placing a brilliantly lighted lamp on the table close to the window in the sitting-room. They invariably came to the light much earlier and were more numerous on dark and drizzling nights than on others that were drier and clearer. The insects were alike in being in perfect condition and coloration, and without carefully removing the viscera and filling their bodies with wadding well powdered with arsenic and chalk it would have been difficult to preserve the specimens from “greasing” when placed in the cabinet. Several large specimens of Porina signata Walker were also taken on the window. From the 10th November until the 9th December, on which date I left the district, the large moths continued to come to the light, though in somewhat diminished numbers. Throughout the spring months of that year (1907) many species belonging to numerous other genera were also more or less abundant, and were in very perfect condition. Owing probably to the excessively humid winter and spring months, some of the specimens exhibited a more or less melanic tone of coloration than in normal seasons.

The dwellinghouse (a wooden structure) referred to is of considerable age, and the window-fittings on both sides were therefore somewhat contracted. In the interstices thus formed several individuals of a large and finely marked native spider, Epeira corrugatum Urquhart (Trans. N.Z. Inst., vol. 16, pp. 72, 73), lived concealed, subsisting chiefly on nocturnal insects becoming entangled in their strong webs. The webs, though irregular in form and structure, were generally constructed across the corner of the panes, with several long and strong threads fastened to the windowframe, near the latch, to give strength and buoyancy to the webs. On several nights, whilst capturing the large moths, I observed several become entangled in the webs. The alert and sensitive spider awaiting concealed in the window-niche, on feeling the struggles of the entangled moth, generally moved slowly and cautiously along the outer strands towards the moth, which it seized, and instantly applied its powerful falx, or poison-fang, to the right side of the moth's thorax. Although the bodies of the large healthy moths would each weigh those of seven or eight spiders, and notwithstanding their being endowed with powerful wings, they were easily overpowered,