81 



TABLE SlIO\VI.\(; rilK I, IKK IIISTOK'V Ol" Kol'i; SI'Ki 1 M K XS 

 "I'ANTAT.A KLAVP:S('EXs'" FABK. 



Egg Average 



or Length in Xo. 1 , No. 2 No. '■] No. 4 Average 



Instar mm. for the 



First Three Days Days Days Days Days 



Egg . . 5 5 5 7 oVz 



1st % —V2- — %* — %* — %* — %* 



2nd 1 4 .5 4 3 4 



3rd 1^/2 3 7 3 41/2 



4th 2V3 2 8 6 2 41/2 



5th 4 3 8 6 3 :. 



6th 5 2 o 5 4 4 



7th 6 3 6 5 5 4% 



Sth 8 2 5 6 6 4% 



9th 10 5 4 9 5 5% 



10th 13 4 9 9 8 71/2 



11th 18 8 13 14 27 11 %t 



12th 24 19 30 30 .. i^Vsf 



Total No. of days 



for growth of nym. 55 98 101 66 80 



Female Female .Male .Alale 



From the above talvle it will be seen that the nvniphs moult 

 ten or eleven times; and that the length of time of incul)ation 

 and especially the total nymphal ]Kn'iod vary considerably in the 

 different indivindals. It will also be noted that the time of the 

 last two or three instars g-radually lengthens, the last, of conrse, 

 being' the longest, averaging (for the fonr) more than one-third 

 (if the life of the nymph. This long period is dne to the great 

 change tliat takes place during the last stadium, — a change 

 from the nymphal water-inhabiting form, breathing chiefly by 

 means of tracheal gills, to the adult form, breathing altogether 

 by means of tracheae. We may say this period corres|)oiids to 

 the pupal stage of those insects possessing a complete metamor- 

 ])hosis. During this time many of the organs are greatly 

 changed; and some are even completely reconstructed, such as 

 the respiratory organs, lalu-um, wings, c(»m])ouud eye<. gizzard, 

 etc. 



In the above experiments the nymphal period varied from 

 55 to 101 days. It is doubtful if the nymphs complete their 

 growth in nature in so short a time as Xo. 1 did in the above 

 experiment, except in very rare cases, as their food su])]dy is not 

 always close at hand ; and the amount of food, modified doubt- 

 less by climatic conditions, largely determines the rate of growth 



* Less than V2 hr. 

 t For 3. 



