114 THE FOOD OF ANIMALS 



spines, and the end-part of the limb can be folded down on 

 these, much as the blade of a pocket-knife shuts down on the 

 handle, so as to form a grasping structure well suited for seizing 

 and holding active prey. The habits of the larva, which when 

 first hatched is a slender creature much like some of the aquatic 

 larvae mentioned earlier, have been described for one of the 

 European species {Mantispes Styriaca). At the time when it 

 makes its appearance certain spiders (of the genus Lycosd) have 

 laid their eggs, enclosed in little bags. One such bag is sought 

 out by each larva, which bites a hole in it, creeps in, and patiently 

 waits among the developing eggs till they hatch out into juicy 

 little spiders, the sad fate of which is to be either at once devoured 

 or else killed and reserved for future use. After a time the larva 

 sheds its skin and becomes a sluggish grub-like creature, which, 

 after making many hearty meals on the reserve spiders, passes 

 through further stages, which result in the appearance of the 

 adult form. 



The Lace-wing Flies {Heinerobiidce and Chrysopidd) are small 

 fragile insects of common occurrence in Britain, and interesting 

 on account of the habits of their larvae, which prey chiefly on 

 aphides ("green fly"). The long slender mandibles may be 

 described as "sucking spears", and are used for piercing the 

 tender bodies of the prey, from which the juices are extracted 

 much as in the case of the ant - lion. Some of these larvae 

 {Hemerobms, certain species of Chrysopa), which, by the bye, 

 have appropriately been termed " aphis-lions ", convert themselves 

 into walking cemeteries by covering their spiny bodies with the 

 shrivelled carcasses of their prey, a bold expedient for making 

 them inconspicuous, others (some species of Chrysopa) use frag- 

 ments of vegetable matter for the same purpose, while others 

 again (most species of Chrysopa) resort to neither of these devices 

 but prowl about unprotected. The Golden-eyed Flies (^Chrysopa) 

 (see vol. i, p. 378) are common British members of the group. 



Dragon-Flies (see vol. i, p. 375). — In most of the neurop- 

 terous insects remaining to be mentioned here the larvae are 

 aquatic in habit. Among the most familiar and attractive of 

 these are the Dragon- Flies, distinguished by their great powers 

 of flight and very perfectly-developed sense organs, the compound 

 eyes being of relatively enormous size. Like bats and swallows, 

 they catch insects on the wing, and may often be seen hawking 



