GALL MIDGES AND GNATS 



and delicate insects known as Gall Midges. The larva 

 of a number of them are gall-makers, producing swellings 

 in the stems of plants, and another species — Contarinia 

 tritici, or Corn Midge — does much harm to oats and 

 barley. It has a cousin called the Hessian Fly {Ceci- 

 domyia destructor), which is also a grain destroyer, but 

 being subject in England to various parasites, its numbers 

 are kept within respectable limits. 



Of the Bibionidcs — or Dung Flies — whose larvae live 

 on decaying vegetable matter, and also consume living 

 roots — ^the St. Mark's Fly {Bibio Marct) occurs in large 

 numbers in Spring. It is all-black, and has long hairy 

 legs. 



Gnats belong to the Cub'cidce, and the Spanish word 

 Mosquito is frequently used instead. Much attention 

 has been devoted to these insects, because of their un- 

 welcome habit of drawing blood from the human body, 

 and as carriers of the fatal germ of malaria. Mosquito 

 brigades have had to be organised to combat their 

 energies, and stirring tales might be told of how man 

 has eventually conquered. The making of the Panama 

 Canal was only made possible after ways and means 

 had been discovered for dealing with these small, but 

 death-dealing parasites. 



The Common Gnat {Culex pipiens, Fig. 37), passes 

 its early life in still water, and the filthier the better. 

 Hence, all standing water should, as far as possible, 

 be done away with, and the breeding quarters reduced 

 to a minimum. The larva floats on the surface with 



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