•20 THE RICE GRASSHOPPER 



coincide, but that the first moult follows the first and 

 precedes the second instar. In fact it is, as it were, the 

 boundary mark between the two stages. One rearing 

 record chosen from a large number kept during the 

 summer and autumn of 1910 is given on the next page. 



This record may be considered as fairly typical 

 and representative. It will be noticed that, in this case, 

 the males of the fifth instar, without exception, had their 

 wing-buds turned upward and that all the males complet- 

 ed their development at the end of the sixth instar, and 

 this is the general rule. All the females, on the other 

 hand, had one more instar and one more moult in their 

 development. The length of time occupied by each in- 

 star can be calculated, with a fair degree of accuracy, if we 

 suppose that the individual moulting first at the end of 

 one instar also moulted first at the end of the following 

 instar and, conversely, that the individual moulting last at 

 the end of one instar also moulted last at the end of the 

 following instar. If we go on this supposition, we get the 

 following results : — 



Instar Duration in davs 



1st ... ... ... 8—9 



2nd ... ... ... 9—11 



3rd ... ... ... 11—13 



4th ... ... ... 10—11 



5tli ... ... ... 10—16 



6th ? ... ... ... 13—15 



6th <? ... ... ... 15—18 



7th ? ... ... ... 11—16 



Total length of developmental period for males 66-78 days, for 

 females 77-82 days. 



This is, of course, only an approximation ; one or two 

 individuals may have taken less time than that noted 

 while, in some cases, they have probably taken a day or so 

 more. On comparing these figures with those of our 

 other rearing records, we find them fairly representative. 

 The duration of the first instar is here rather shorter than 

 usual. In other cases, it has lasted from eleven to sixteen 

 days. With regard to the total length of the develop- 

 mental period, the following records, in addition to the 

 above, may be of interest : — 



1 a. Record of 14 males: — 



Hatched, 15-6-10. First assumed adult form, 29-8-10. 

 Last assumed adult form, 21-9-10. 

 Length of developmental period 75-98 days. 



