DEVELOPMENTAL STAGES 19 



observation here. It is impossible to state definitely, from the length 

 of a young Rice Grasshopper, the instar to which it belongs. On the 

 other hand, the length of the antennae and the number of segments 

 they contain are much more constant and, by means of these two 

 factors, combined with an examination of the development of wing- 

 buds and external sex organs, it is a comparatively simple matter to 

 place the developing hopper in its proper instar, a matter of consider- 

 able importance in deciding, in any particular case, the time at which 

 the insect can best be combated. 



The above account of the developmental stages has 

 been made somewhat full from the fact that the}^ have 

 never been fully described before and also from the fact 

 that the hnperfect accounts we have are inaccurate. 

 Lefroy/ in his "Indian Insect Pests," gives the following 

 short statement of the development : — " They (the young 

 grasshoppers or nymphs) are at first dark-coloured with a 

 green dorsal stripe but later become green. . . . They un- 

 dergo the usual five moults and become full-grown in 8-1 

 weeks." From this, one is led to expect to find half-grown 

 hoppers invariably green, whereas, in our experience, only 

 comparatively few are green during development, the 

 majority not assuming this color till they become adult. 

 The statement with regard to the number of moults is 

 also incorrect. All the individuals, numbering over a hun- 

 dred, of which we have kept a record, underwent at least 

 six moults, while the females invariably and the males 

 occasionally underwent an extra moult, making seven 

 moults in all. While our investigations have been made 

 in Southern India, it is still hardly likely that there should 

 be such a difference in the life-history of the insect in 

 different parts of India as would appear from these two 

 accounts. 



In the above account of the development of the Rice 

 Grasshopper, no reference was made to the length of 

 time occupied by each instar. As a matter of fact, there 

 is a certain amount of variation in this respect, some in- 

 dividuals growing more rapidly than others. It may be 

 roughly stated, however, that each instar occupies from 

 ten to fifteen days. The accompanying table contains a 

 record of rearings carried out in the insectary in Bangalore, 

 and indicates the number of moults undergone and the 

 length of time which expired between each two moults. It 

 should again be noted that moults and instars do not 



1 Loc. cit., page 120. 



R. G. C2 



