ENEMIES OF APHIDES. 257 



existence, destroying and making an increasing war upon the 

 other denizens of the water whom they are sufficiently powerful to 

 overcome. 



But while in the more open spaces the quick movements and 

 untiring flight of these striking flies attract the eye, a more beau- 

 tiful variety of the same order, of heavier flight and less metallic, 

 though more elegant colouring, will often be seen beneath an over- 

 hanging oak or an aged elder, fluttering clumsily from bough to 

 bough, and sometimes leaving upon the leaves or stems where it 

 has pitched a white spot resembling a speck of mildew. The 

 insect belongs to the sub-family of Chrysopida, which, with the 

 Heiiierobiidce anc^ ConiopterygidcE^ constitute the family Heinero- 

 biincE, the larvae of which are Aphis eaters. 



The larger of these flies, and especially the Chrysopidce, are 

 known popularly as "lace-wing flies," from the gauzy and peculi- 

 arly web-like texture of their ample wings, and sometimes as 

 " golden eyes," from the metallic, brassy appearance of their very 

 prominent eyes. The exquisite grass tint general in this sub-family 

 which pervades even the nervures of the delicate wings, prevents 

 their being readily detected, except when in actual flight, but the 

 presence of the female may often be judged by the white 

 spots already mentioned upon the leaves, or by a line of small 

 white excrescences upon some adjacent twig, such spots, in 

 truth, being but groups of the curious pedunculated eggs which 

 have attracted the attention of many generations of naturalists. 

 The female fly of C/uysopa perla, the species which being most 

 common in Britain is most conveniently studied, when about to 

 oviposit, touches with the extremity of her abdomen the surface 

 of a suitable leaf, leaving thereon a minute speck of glutinous 

 substance secreted by special glands, subservient to the organs of 

 reproduction. She next lifts her body, and from the leaf to the 

 ovipositor there stands a tiny white pillar of whalebone-like flexi- 

 bility, to the extremity of which an egg, escaping from the 

 ovipositor, seems to attach itself and remains erect, the patient 

 insect re-commencing its task and continuing until about ten or a 

 dozen eggs are similarly placed. Such a group is shown on Plate 

 XII. at Fig. I, where may be observed the curious precaution 

 taken by the fly lest the foundation of her supports should be 



