60 FRO<;iIOPP£R liLIGIIT OF SUGAR-LANE. 



Stage I. (Fig. 9 A.) Total length 1-2 mm. Pale yellowisli browu 

 with a faint reddish mark on each side of the abdomen. No traces of wing 

 rudiments on hind margin of either meso or meta-thorax. Antennae five 

 segiBented, lengths of segments in millimetres : — 1, 0"03 ; 2, 0*0B ; 3, 0'03 ; 

 4, O-O? ; 5, 0-04 ; Total length of antenna 0-15 mm. 



Staffe II. (Fig. 9 B.) Total length 2-6-3-6 mm. Pale yellowish 

 brown in coloin-. Hind angles of the meso and meta-thorax very 

 slightly produced indicating the rudimentary wings. Antennre six 

 segmented. Length of segments in mm.: — 1, 0*08; 2, 0'06 ; 3, 0*08 ; 

 4. 0-0.5 ; 5, 0-05; 6, 0-06; Total length of antenna 0-40 mm. 



Stage III. (Fig. 9 C.) Total length 4-5*5 mm. Head and thorax 

 pale brown distinctly darker than the rest of the body. Wing rudiments 

 quite distinct but scarcely longer than wide at the base. Antennae seven 

 segmented. Lengths of segments in mm. 1, 0'13 ; 2, O'll ; 3, 0'15 ; 

 4, 0-09 : 5, 0-08 ; 6. 0-07 ; 7, 0-08 ; Total length of antenna 0-72 mm. 



Stage IV. (Fig. 9. D.) Length 6-5-8-0 mm. Head, thorax and 

 wing rudinaents brown, abdomen yellow. In nearly mature specimens 

 the colour of the adult shows through inth-elegs, body and wings. Wing 

 rudiments longer than broad at the base and reaching to the third 

 abdominal segment. Antennte eight segmented. Length of segments 

 in mm. 1, 0-20; 2, 0-16; 3, 0-30; 4,0-18; 5,0-20; 6,0-10; 7, 0-14; 

 8, 0-12. Total length of antenna about 1-38 mm. 



HABITS OF NYMPH. 

 The nymphs suck the sap from the roots of the food plant at and below 

 the surface of the ground. They may be quite exposed on the surface, 

 (Plate III.) but more usually prefer the conditions and the soft roots 

 developed under heaps of trash lying on the surface. In well broken 

 soil the greater number seem to be at a depth of from two to four inches 

 but many descend still lower than this and may be found occasionally 

 as deep as eight or ten inches below the surface. 



Above the ground they are sometimes found feeding on the adventi- 

 tious roots of the cane beneath the leaf sheaths, and in such a position 

 they have been seen over two feet from the ground. This refers to the 

 feeding and developing nymph; when full fed, however, those below 

 ground normally come up to some point a little above the surface where 

 they make a final froth chamber in which to moult to the adult. In most 

 cases there is no feeding when in this position and the froth must be 

 made fi-om reserve material. 



These last moulting chambers are usually only a few inches above the 

 surface on some grass blade or cane stalk, but they have been seen as 

 high as three feet from the surface. After the adult leaves this chamber 

 the froth dries and retains its shape for some da^'s. 



THE FROTH. 



The froth round the n^-mph is one of the remarkable characteristics 

 of the Cerc02nd(P or Froghoppers. It consists of a gummy liquid 

 secreted by the alimentai';\- canal, in which air bubbles are blown by 

 the insect by means of its breathing system, which opens ventrally into 

 a chamber formed beneath the abdomen by the overlapping sides of 

 the latter. 



The nymph may readily be watched protruding the end of the 

 abdomen from the froth to take in a supply of air and then withdrawing 

 it into the froth and forming a bubble beneath the surface. 



The gummy substance which gives the excreta of the nymph its 

 viscosity and tenacity is, according to Kershaw, a mucin or a mucinoid 

 and is produced in his opinion by the antei-ior portion of the malpighian 

 tubes (Kershaw 1913 C. p. 3). He states that "if part of a nymphal 



