CHAPTER IX 



INSECTS IN RELATION TO OTHER ANIMALS 



i. THE GENERAL SUBJECT 



On the one hand, insects may derive their food from other 

 animals, either living or dead ; on the other hand, insects them- 

 selves are food for other animals, especially fishes and birds, 

 against which they protect themselves by various means, more 

 or less effective. These topics form the principal subject of 

 the present chapter. 



Predaceous Insects. Innumerable aquatic insects feed 

 largely or entirely upon microscopic Protozoa, Rotifera, Ento- 

 mostraca, etc. ; this is especially the case with culicid and chi- 

 ronomid larvae. Many aquatic Hemiptera and Coleoptera 

 prey upon planarians, nematodes, annelids, molluscs and 

 crustaceans; Bclostoma sometimes pierces the bodies of tad- 

 poles and small fishes ; Dytiscus also kills young fishes occa- 

 sionally and is distinctly carnivorous both as larva and imago. 

 Among terrestrial insects, Carabidae are notably predaceous, 

 preying not only upon other insects but also upon molluscs, 

 myriopods, mites and spiders. Ants do not hesitate to attack all 

 kinds of animals; in the tropics, the wandering ants (Ecitoii) 

 attack lizards, rats and other vertebrates, and it is said that 

 even huge serpents, when in a torpid condition, are sometimes 

 killed by armies of these pugnacious insects. 



Mosquitoes affect not only mammals but also, though 

 rarely, fishes and turtles. The gad flies (Tabanidae) torment 

 horses and cattle by their punctures; and the black-flies, or 

 buffalo gnats (Simulium), persecute horses, mules, cattle, 

 fowls, and frequently become unendurable even to man. The 

 notorious tsetse fly (Glossina morsitans) of South Africa 

 spreads a deadly disease among horses, cattle and dogs, by 



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