7 6 



Observe how beautifully certain hairs resembling fan- 

 palm leaves are shewn (palmate hairs) (Fig. 65). 



2. The Method of Feeding of Anophelines. 

 Observe with a lens the action of the feeding brushes 

 and the currents they produce on the surface of the 

 water. Note the rotation of the head so that, whilst 

 feeding, the ventral surface of the head is uppermost. 



3. The Food of Larvae. Tear a larva to pieces 

 with a needle and remove a small portion of the dark 

 central mass of food material filling the straight 

 alimentary canal. Place in a drop of clean water and 

 crush under a coverglass. Note what organisms form 

 the chief bulk of the food. Note the presence of sand 

 grains, unicellular plants and animals, short lengths 

 of alga, diatoms, bacilli, etc. 



Determine the common foods of several species 

 of Anophelines. 



4. Desiccation of Larvae. Celli and Casagrandi 

 have found that Anopheline larvae can only resist 

 desiccation at 20 C. for two days, at 35 C. for one 

 day, and 40 C. for two minutes only. Larvae of 

 Anophelines stranded on moist mud will live as long as 

 four days, but in the tropics as soon as the mud loses 

 its glistening surface they die. 



5. Cannibalism of Larvae. Add some large 

 Gulex larvae to a small bottle containing some small 

 larvae or Anopheline larvae. The Anopheline larvae 

 or small Culex larvae will be devoured by the large 

 forms. Mucidus sp., C. concolor, and Psorophora sp., 

 are especially cannibalistic. 



6. Observe the occurrence in nature of Culicine 

 and Anopheline larvae, also what Culicine larvae are 

 found living together. 



7. The Enemies of Larvae. Add small fish, water- 

 beetles (Dytiscidae, Hydrophilidae), and their larvae, 



