G16 THE MICROSCOPE. 



posed to be the saliva of the cuckoo, being found on the 

 •young shoots of plants just about the time the cuckoo is 

 heard in the woods. 



The Hymenoptera are distinguished from other insects 

 with membranous wings by the presence of an ovipositor 

 of peculiar construction at the extremity of the abdomen 

 of the females, which serves for placing the eggs in the 

 required position ; and in the males of some (Bees, Wasps, 

 &c.) constitutes a most formidable offensive weapon. As 

 the structure of this organ, which is rarely absent, is 

 essentially the same throughout the order, the form of its 

 component parts being merely modified to suit the exigencies 

 of the different insects, a short description of its structure 

 will not be considered out of place. The ovipositor, 

 borer, or sting, generally consists of five pieces : a pair of 

 horny supports (fig. 279) forming a sheath for the borer 

 or ovipositor, being jointed at the point where they issue 

 from the cavity of the last abdominal segment, and the 

 last joint is usually as long as the borer itself. The latter 

 consists of three bristles, of which the superior is grooved 

 along its lower surface, for the reception of a pair of finer 

 styles, and these are barbed at the point. The three 

 pieces, when fitted together, form a narrow tube, through 

 which the eggs j^ass to their destination, the poisonous 

 fluid also, which renders the sting of the Bee so painful, 

 is forced down the same into the wound. In the Saw-fly, 

 a part of this organ remains rudimentary, in other respects 

 it does not very much differ. 



The larvae of most Hymenoptera are footless grubs, 

 furnished with a soft head, and exhibiting but little, if 

 any, advance upon those of Diptera (Plate VI. No. 141). 

 In the Saw-fly, however, the larva, instead of being, as 

 above described, a mere footless maggot, presents the 

 closest resemblance to the caterpillar of the Lepidoptera ; 

 it is provided with, a distinct head, with six thoracic legs, 

 and in most cases, from twelve to sixteen pro-legs are 

 appended to the abdominal segments. 



The Saw-fly, fig. 276, most destructive to the goose- 

 berry-bush, is remarkable for the way in which the female 

 provides for the safety of her eggs. This fly has a flat 

 yellow body, and four transparent wings, the outer two ot 



