NATURAL HISTORY OF SOUTH AFRICA 



MOSQUITOES 



Of the many insect pests which plague mankind, 

 the mosquito is by no means the least. The female 

 mosquito lays its eggs in water. Some species deposit 

 their eggs on the surface of the water in adherent 

 clusters, while others (anopheles) lay them singly. 

 Stagnant and sheltered pools, ponds, ditches, marshes, 

 and water in tubs, old tins, etc., are preferred, because 

 (i) any disturbance of the surface by wind, or motion 

 of the water in running, prevents the larvae from coming 

 to the surface to breathe ; (2) stagnant water contains 

 an abundant supply of the minute vegetable and 

 animal organisms on which the mosquito larvae feed. 

 They do not breed in brackish water. Each female 

 mosquito lays about 300 eggs at a sitting, and if it 

 survives its enemies it will lay several more batches 

 before the cold of winter kills it. A few hours after 

 being laid the eggs hatch. The larvae are small 

 blackish creatures, more or less similar in shape to a 

 caterpillar. They are obliged to come to the surface 

 of the water every few minutes to breathe. Advantage 

 is taken of this fact to cover the water with a thin film 

 of paraffin, which stops up the breathing tube of the 

 larva and kills it. After about ten days the larva or 

 wriggler changes into a pupa or chrysalis. If the 

 water remains at a suitable temperature, the pupa, 

 in about twenty hours, finally comes to the surface and 

 rests there, and from it a fully-developed mosquito 

 emerges and flies away. After feeding and mating, 



270 



