HYMENOPTERA. 



CHAPTEK T. 



Sm' FLIES. 



This order of insects is easily known by the structure of the 

 wings. These organs are four in number, membranous, and 

 without either scales or hairs. The second pair are always 

 smaller than the first, and have not nearly so many veins. 

 During flight these two pairs of wings are connected together 

 by a series of little hooks, so that they practically form one 

 single pair. The mouth is furnished with horny jaws, and the 

 females possess an ovipositor, which either takes the form of a 

 saw-like instrument, as in the Saw Flies, or a sting, as in the 

 bees, wasps, and ichneumon flies. In some cases, as in the 

 ants, the wings are not present in all the individuals, and the 

 reader will remember that the same is the case with the 

 Termites, which have just been described. 



Their number is absolutely enormous, and even in our own 

 country from three to four thousand species of Hymenoptera are 

 known. In this land they do not attain any great size, our 

 largest Hymenopterous insect being the well-known Humble 

 Bee, but in various parts of the world some species grow to a 

 considerable size, as we shall presently see. 



We begin our account of the Hymenoptera with the Saw Flies, 

 so called from the curious structure of the ovipositor. This organ 

 is intended for the deposition of eggs in slits which are cut in the 

 bark or the leaf-stems of various trees and plants, and is made in 

 a very beautiful manner. There are scarcely any two genera of 

 Saw Flies in which the ovipositor is made in exactly the same 

 manner, so we must content ourselves with a general description, 

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