Hie Inheritance of Colour in Carausius morosus. 113 



first instar. The first moult leading to the second instar occurred on 

 May 19. The only traces of brown left were the brown band on the side of 

 the head and very faint traces (discernible only under close examination) of 

 the other bands. The second moult leading to the third instar occurred on 

 June 12. After it the same traces of brown were discernible as in the 

 second instar, but after the third moult on July 1 all traces of brown except 

 a few tiny dots on the dorsal surface of the thorax and of the abdominal 

 segments had disappeared. After the fourth moult on July 24 nothing but 

 green was discernible. This continued after the fifth moult on August 22 

 except for the appearance of a slight tinge of red on the anterior edge 

 of the femora of each of the first pair of legs. After the sixth moult on 

 September 14 the red tinge had developed into a band of pale pink. After 

 the seventh and last moult on October 18 the band of pink had become 

 bright vermilion, and the eighth or adult instar had been reached. A month 

 later egg laying began, and on an average one egg was laid per day during 

 the hours of darkness. 



Table of Length of tlie Various Instars. 



(Compiled from 12 insects.) 



mm. 



1st instar 11-14 



Pi* 2nd „ - 14-19 



ggg V.Srd „ 20-25 



4th „ 27-31 



5th „ ..; 33-40 



6th „ ; 45-52 



7th „ 59-67 



8th „ (adult) 70-81 



Duration of Instars. 



(Compiled from 8 insects kept at a temperature of 40~-60 c F.) 



, days. 



1st instar 13-19 



2nd „ 14-22 



3rd „ 20-25 



4th „ 19-34 



5th „ 24-31 



6th , 25-32 



7th „ 35-47 



As we have stated below all insects are hatched alike in colour pattern, 

 and the change to pure green takes place after the first moult and is 

 complete after the third. After the first moult also a change to brown may 

 occur as shown in fig. 5. 



