144 ANIMAL PHYSIOLOGY. [LESSON 41. 



LESSOJST XLI. 



NUTRITION IN INSECTS, CONTINUED. 



644. The Neuropterous insects are, for the most part, predace- 

 ous and carnivorous ; always killing their prey on the wing, they 

 have hence been called " the Hawks amongst insects." 



645. The most conspicuous insects of this order, and the best 

 known, are the bold and beautiful dragon flies, or, as they are called 

 in this country, "Devil's darning needles." Furnished with a head 

 almost all eyes, their sight is wonderfully piercing ; provided with 

 large, light wings, constructed of the most gauzy material, and abun- 

 dantly supported by an incredible number of the lightest conceivable 

 bones, their flight is as remarkable for its swiftness as their aim is 

 unerring. It is a pretty sight to see these creatures Hawking over a 

 pond, and remarkable the distance at which they see an insect once 

 seen, its death is certain ! Our obligations are great to this order 

 of insects, for they kindly free us from millions of pests, alike de- 

 tractive of our property and sorely tormenting to our persons. It 

 has pleased the Almighty dispenser of good to set up no end of an- 

 tagonisms in nature wherever a bane exists, there is the antidote ; 

 what a pity that man, in the plenitude of his ignorance, should take 

 so much pains always to destroy the antidote ! So important are 

 these insects, it is not too much to say that he who wantonly kills a 

 dragon fly commits a public wrong. 



646. The smaller species of Libellula (Agrion), with a body less 

 in diameter than a moderate sized pin, consume immense quantities 

 of Mosquitoes, at the moment, too, when they emerge from the water 

 and assume the winged state. 



647. The habits of other insects 

 frequently change with a new form, 

 but, whether as an inhabitant of 

 the water, or a denizen of the at- 

 mosphere, the dragon flies are al- 

 ways cruelly carnivorous, and as 

 such should be cherished. 



648. The mouth of a Dragon 

 fly is mandibulate (Fig. 238). The 



Upper part of month, Libellul, U PP 6r K P M is * el1 formed > the U f 



per jaws (b) are short, remarkably 

 strong, possessing toothed processes, and supplied with muscles for 



