The Variety of Substrata 63 



air-water interface presents an excellent feeding ground. By pinching 

 the surface film with its specially adapted mouth parts the larva ob- 

 tains the food material and causes more distant particles to move 

 nearer the area of its activity. In this way the larva is said to be 

 able to gather food from a circle perhaps 30 cm in radius around its 

 point of attachment. 



Anophelines 



Culicines 



Anopheles 



Aedes 



Culex 



CS^^J^I 



I 



Eggs 



(floating 

 on water) 



«;fo"^ 



Water 



— surface 



Fig. 3.1. Diagram of life cycle of mosquito, showing the use of the water surface 



as a substratum in the early stages. The larvae use the surface fibi not only for 



support but also for a feeding ground. 



Another special substratum of interest is wood. In the air environ- 

 ment "dry rot" fungi, termites, and other organisms find this material 

 a suitable substratum for their activities and for their nourishment. 

 Far from human habitation the destruction of dead timber by these 

 plants and animals merely aids in the reduction of organic materials 



