350 G. E. BODKIN AND L. D. CLE ARE. 



presence of a small heap of whitish, almost transparent exuviae. On emergence 

 a rest is taken to allow the chitin to harden. Under natural conditions the eggs 

 appear to hatch during the earliest morning hours. 



Development of Hoppers. 



The complete life-history has been worked out in the insectary of the Biological 

 Division. On their emergence a number of the young hoppers were isolated in 

 suitable glass receptacles and regularly supplied with fresh leaves of cassava 

 (Manihot utilissima). Others were also allowed to develop in a spacious cage 

 constructed of glass and wire, which allowed the insects freedom of movement 

 and a maximum quantity of light and air. 



Careful records were kept of each stage. The life-history thus worked out 

 proved to be slightly shorter than under field conditions. Feeding took place 

 mostly during the night. 



First Nymphal Stage. — In two or three weeks the eggs hatch and the nymphs 

 emerge by a longitudinal rupture. The nymphs are a light pea-green in colour, 

 with dull black markings and spots, and are covered with fine light-coloured hairs. 



Fig. 3. First stage nymph. 



The antennae are black, the base of each segment being yellow. There is a black 

 meso-dorsal line and the hind femora show three broad bands of black. 



Length . . . . . . . . . . 9'0 mm. 



Length of hind femora . . . . . . 5'0 mm. 



No. of segments of antennae . . . . 14 



About four days after emergence the nymphs become much darker and assume 

 a blackish tinge. This change in colour is so noticeable that it can almost be taken 

 for another nymphal stage, but in reality, it is only the colouration from below and 

 precedes the 2nd nymphal stage by some four days. When the change to the 

 second nymphal stage does take place it can be easily recognised and shows that the 

 darkening in the 1st stage was really due to the colouration below. 



Second Nymphal Stage. — In this stage the insects can almost be considered 

 black with light markings. The dorsal line has broadened considerably and extends 

 the entire length of the insect. Two broad lateral lines of black have now 

 appeared, which almost cover the whole of the lateral areas and are only separated 

 from the dorsal one by narrow stripes of a pinkish yellow colour, the insect thus 

 appearing black with lighter markings. The head, too, is mostly black, the vertex, 

 the clypeus and the mouth-parts being of this colour, while the genae bear a stripe 

 of the same colour ; the antennae are black. The legs are also largely black ; 



