372 



Destruction of Gnats. 



[sept. 



There are several species of gnats, but speaking generally all 

 gnats have the following life-history. The eggs are laid by the 



by means of a small tube which projects from the hinder region 

 of the body, and which is thrust above the surface of the water. 

 On this mode of respiration is founded one of the measures de- 

 scribed below for combating the gnats. When the larva is full 

 grown it becomes a pupa, the pupal stage also occurring in the 

 w^ater. When this stage is completed the pupal skin bursts, and 

 from it the adult emerges, and, after its wings and other external 

 parts have dried and hardened, it flies off. The egg, larval and 

 pupal stages all need water for their development, and water in 

 some form is always the source of any case of infestation of gnats. 

 The following are likely places for the breeding of the pests : — 

 Open water butts ; cisterns without covers ; tanks of any kind 

 without covers and containing water ; open pieces of water from 

 vvhich water may be drawn for garden and conservatory ; 

 ditches ; large and small puddles (for the larvae can be bred to 

 maturity in quite shallow water) ; pools. 



If such breeding places be destroyed, and egg-laying is pre- 

 vented, no adults can be formed. 



Careful attention should, therefore, be paid to water barrels, 

 butts, and exposed cisterns and tanks, which should be covered 

 with boards. If the covering boards fold so that chinks are 

 left, these chinks must be covered over to prevent the eggs 

 reaching the water. 



Puddles and similar pieces of water should be filled in with 

 earth or other material, while ditches and other places that 

 cannot be filled up should be well drained. Ponds or sheets of 

 water should be examined, and if any larvae are found, a bundle 

 of rags should be dipped in paraffin and the paraffined rags 

 drawn over the surface of the pond on a quiet day. The result 

 will be that the surface of the water will be covered with a thin 

 film of paraffin, and, the breathing tubes of the gnat-larvae fail- 

 ing to pass through the paraffin, all the larvae will be suffocated. 

 This treatment should be repeated every week as long as the 

 larvae are found. 



Destruction 

 of Gnats. 



females in water, and from these larvae are 

 hatched out, which are entirely aquatic in 

 habit. These larvae breathe air taken in 



