140 A. INGRAM AND J. W. S. MACFIE. 



as we have stated, is poised on the dorsal margin of the " common hollow space "as 

 its fulcrum. The six sets of terminal hooks no doubt suffice to anchor the larvae 

 once they have penetrated the plant tissues. In specimens killed and fixed in situ 

 and subsequently cleared, the siphon is seen to be embedded in the root up to a point 

 about half-way between the tip of the tube and the bases of the dorsal bristles, the 

 booklets at the end are spread out in a cluster and appear to be firmly fixed in the 

 tissues, and the dorsal and ventral bristles of the sirjhon. are widely extended with 

 their tips in contact with the surface of the root. 



The siphon of the larva in the first instar bears but a slight resemblance to that of 

 the fully- developed larva, it is a bottle-shaped structure, which is made up of a conical 

 basal portion (8*5 units) and a more highly chitinised and slender apical portion 

 (7*5 units). The basal ring is hardly visible, the movable junction between the apical 

 third and the basal portion is indistinguishable, but the chitinised axial rod is well 

 developed and has powerful muscles attached to it in the lower half of the tube. 

 About half-way up the lower part of the siphon and slightly on the ventral aspect, 

 that is, in the position occupied by the tuft in the fully-developed larva, there is a 

 single, very long, simple hair. At the shoulder of the bottle, that is, at the point 

 where the narrow part of the siphon commences, the tracheal trunks are constricted, 

 and from this level run up the distal end of the siphon as two chitinised tub^s separated 

 by the axial rod. At the tip of the siphon on the ventral aspect there is a pair of 

 powerful highly chitinised double hooks, corresponding with the similar triple hooks 

 of the fully developed larva ; dorsally there are two pairs of less highly chitinised 

 hooks, which are toothed ; and a pair of relatively stout bristles mounted on large 

 bases can be distinguished, which appear to represent the dorsal bristles of the later 

 stages. The saw-like structure on the dorsal aspect is not developed at this stage. 

 The relatively poor development of the terminal structures is no doubt associated 

 with the habit of the larva in this instar of attaching itself to the rootlets instead of 

 to the tougher tap-root. 



The larva at this stage, the first instar, differs in many other respects from the fourth 

 phase larva. The head is large, considerably larger than the thorax ; the antennae 

 are relatively huge, possessing the two prominent bristles which are conspicuous in 

 the fully-grown larva, and have in place of the tuft a single stout branched hair. 

 The mental plate is small and has three slender lateral teeth on each side of the 

 prominent mesial tooth. The eyes are prominent and rounded ; the " main " eye 

 is not yet developed. The lateral abdominal hairs are two on the first, and one on 

 each succeeding segment. The comb consists of three to five fringed spines, quite 

 unlike the curious elements of the comb of the fully-developed larva. The tuft on 

 the siphon is represented by a simple stout hair, and all the plumes of the eighth 

 segment are in this stage simple hairs. The dorsal hairs on the anal segment are 

 conspicuous, arranged in pairs, the ventral pair being shorter than the dorsal ; there 

 is no beard. The anal papillae are equal, and have rather less sharply pointed ends 

 than those of the fully grown larva. 



After the first moult the siphon assumes the form described as being characteristic 

 of the species. The dorsal saw-like structure is well developed in the second instar, 

 but has rather fewer teeth than in the fully developed larva. 



