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Show 1880.] PROF. WESTWOOD ON THE GENUS PERGA. 375 attendance on the Larva by an Insect of the Tribe of Terebrantia, belonging to the Genus Perga, observed at Hobarton, Tasmania." The female insect deposits her eggs in a longitudinal incision between the two surfaces of the leaves of one of the Eucalypti, adjoining the midrib. The eggs, about eighty in number, are placed transversely in a double series. They are of an oblong form, two lines in length and half a line in breadth. On this leaf the mother sits till the exclusion of the larvae (which takes place in a iew days) ; nor can she be made to leave the spot except by actual force, "clinging to the edges of the leaf by her flexible tarsi. The larvae, when hatched, are of a dirty-green colour, with shining black heads : they keep together in the brood, arranging themselves in oval masses with their heads pointing outwards. They appear to feed chiefly by night; the mother insect sitting with outstretched legs over her brood, preserving them from the heat of the sun and attacks of their enemies with admirable perseverance, never offering to use her wings (even when disturbed) or moving from the spot. Instances are mentioned where two mother insects were found tending one large brood, a smaller adjacent one being without the parent; and, although so anxious in the defence of the young, they allowed themselves to be transposed to other broods, which they tended with equal assiduity for a period of from four to six weeks. They were, however, never observed to render any direct assistance to the larvae ; indeed the broods which had been accidentally deprived of their mothers were still in a thriving state. Previously to casting their skins, the larvae arrange themselves in an oval mass with their heads pointing outwards, and the anterior legs elevated, resting on the four posterior only. The remainder of the body is likewise thrown upwards ; and their tails meet in the centre, forming a conical mass, concealed in the midst of which are the small and feeble individuals of the brood. In a subsequent communication Mr. Lewis states that there is but one brood in the year, and the earliest portion of their lives is passed during the winter season, when they are subject to heavy rains. When resting in the day the larvae, like those of most other Terebrantia, carry their heads erect, emitting a drop of a yellow gummy fluid from the mouth; and if touched they throw their heads back and vomit this fluid in some quantity. It is very thick, and seems to be given to them as a protection against Ichneumonidae, one of which tribe preys upon them ; but the author had seen one of the Ichneumons dead with the wings and legs covered and glued together by this gummy matter. 29. PERGA SMITHII, Westw. (Plate XXXVI. fig. 6.) Fcemina gracilis. P. lewisii similis, at multo minor, pallidior, abdomine nitido lutescente, dimidio apicali castaneo, tibiarum posticarum apice et articidis tarsorum posticorum apicibus nigris. Long. corp. lin. 6-7. Expans. alar, antic, lin. lOj-12. Hab. in Australasia. In Mus. Hopeiano. P.ferruginece, Leach, affinis, differt corpore gracihore, abdominis dimidio apicali obscure castaneo; tarsis elongatis, posticis nigro an. |