84 



genera of the Culicidae are not nearly so great as in 

 the case of the larvae. 



By keeping under observation a number of 

 nymphae, some will be seen to become less inclined 

 for active movement, and the abdominal segments 



Fig. 30. Nym-phae of an Anopheline and Culex sp. 



(tail) may be extended horizontally. Soon after these 

 changes the adult insect emerges through a crack in 

 the chitin of the back of the thorax. The process as 

 seen in Anopheles is very fully described by Nuttall and 

 Shipley. 1 



EXAMINATION OF NYMPHAE 



1. Observe that when first they appear the 

 nymphs are light in colour, but darken very considerably 

 later. 



2. Note that just before the hatching of mos- 

 quitoes the nymph lies with the tail extended, and that 

 silvery marks may be seen, due to air lying under the 

 chitin. 



3. Observe the emergence of the imago. 

 Examine the nymphs of Anophelines, Culex, 



i. Journal Hygiene, vol. I, part II. 



