282 INDIRECT BENEFITS DERIVED FROM INSECTS. 



renewing the operation till no more are to be found. He 

 also climbs trees in search of wood-lice and wild-honey. 

 Bats, as every one knows, are always flitting about in 

 summer evenings, hawking for insects : and the Lemur 

 and monkeys will also eat them. 



Insects likewise afford a favourite kind of food to many 

 reptiles : the tortoise ; frogs and toads ; and lizards too 

 of different kinds. St. Pierre mentions a small and very 

 handsome species in the island of Mauritius, that pur- 

 sues them into the houses, climbs up the walls, and even 

 walks over glass, watching with great patience for an 

 opportunity of catching them *. The common snake also 

 is said to receive part of its nutriment from them. 



But to revert to insects as indirectly advantageous to 

 us, by furnishing food to fishes and birds, beginning 

 with the former. 



Our rivers abound with Jisli of various kinds, which 

 at particular seasons derive a principal part of their food 

 from insects, as the numerous species of the salmon and 

 carp genus. These chiefly prey upon the various kinds 

 of Trichoptera, in their larva state called case- or caddis- 

 worms, and in their imago may-flies (though this last 

 denomination properly belongs only to the Sialis lutaria, 

 which generally appears in that month,) and Ephemercc. 

 Besides these, the waters swarm with insects of every 

 order, as numerous in proportion to the space they 

 inhabit, as those that fill the air, which form the sole 

 nutriment of multitudes of our fish, and the partial sup- 

 port of almost all. 



Reaumur has given us a very entertaining account 

 of the infinite hosts of Ephemeraj that by myriads of 

 ^ St. l^ierre, Vojj. 73. 



