86 



Place nymphae in drops of water on a slide and 

 examine the air syphons. They appear to be of special 

 value in the differentiation of genera. 



1. Anophelinae. The syphons have a square 

 truncated end, and are proportionately much shorter 

 than in Culex, and project from about the middle of 

 the thorax (Figs. 30 and 31). 



2. Culex. The syphons are long and narrow, 

 and have an oblique opening, and project from the 

 posterior portion of the thorax (Figs. 30 and 31). 



3. Stegomyia and Desvoidea. The syphons are 

 broadly triangular, and are characteristic. Note the 

 marked contrast in appearance to those of Culex 

 (Fig. 32). 



Fig. 32. Nympbal Syphon lube of Stegomyia 



4. Corethra and Mochlonyx. (a) Note in Corethra 

 the pointed syphons with slit-like opening and the 

 straight tail (Figs. 31 and 33). 



(b) Note in Mochlonyx the CW^r-like nymph and 

 the thin rounded and pointed syphons with circular 

 opening (Fig. 31). 



5. Chironomus. Examine the bottoms of pools 

 of polluted water, and note in the mud the brilliant red 

 nymphs and larvae of Chironomus (Fig. 33). 



I. Note that-- the nymph has a large globular 

 body (head and thorax) and bears a general resemblance 

 to mosquito nymphs. 



