THE SAND WASPS. 



497 



almost every case, the caterpillar bears the seeds of death within its body in the 

 shnpe of tiny white grubs, like very minute grains of rice. These creatures are the 

 young of an Ichneumon-fly (Microgaster glomerdtus), and retain their place within the 

 caterpillar until the time for it to change into the perfect form. They then simul- 

 taneously eat their way out of the skin, spin a number of bright yellow silken cocoons, 

 and in process of time change into tiny flies and set out on their destructive mission. 

 The caterpillar never survives their attacks, and is seldom able to move away from the 

 spot whereon it happened to be when the Ichneumons make their escape, the body 

 being enveloped in their yellow cocoons. 



All the Ichneumon-flies may be distinguished by their fussy restless movements, as 

 they run up and down any object on which they may settle, and the continual quiver- 

 ing of their antennae. The two lower figures in the illustration belong to this family, 

 that on the left showing an example of the long ovipositor with which several species 

 are furnished, and the other being given in order to show the wasp-like abdomen and 

 the curled antennae. 



The Rhyssa persuasoria is the largest British Ichneumon, and is parasitic on Urocerus 

 jurcHcus, another species of the same genus as that to which the giant Ichneumon 

 belongs. The larva on which it preys bores deep holes in fir-trees, and, in consequence, 

 the Rhyssa may be seen running up and down the trunks in search of some spot where 

 the ovipositor may be introduced so as to lodge in the hidden larva. So deeply does 

 the insect contrive to force its weapon into the wood, that it sometimes is unable to 

 withdraw it, and may be seen hanging dead and dry to the tree in which it has buried 

 the ovipositor too firmly. 



PASSING by several families be- 

 longing to this group, we must 

 briefly mention the beautiful RUBY- 

 TAIL FLIES, or CUCKOO FLIES, or 

 Chryisdidae, so plentiful in sum- 

 mer about old walls and similar 

 localities. These are distin- 

 guished by the fact that, in the 

 females, the last segments of the 

 abdomen are formed into a tele- 

 scopic tube, which can be projected 

 or retracted at pleasure, and is 

 furnished with a minute sting. 

 These are, perhaps, the most bril- 

 liant in color of any British insect, 

 and are veritable humming birds 

 of the insect tribes, their bodies 

 literally flashing with ruby, sap- 

 phire, and emerald, as they flit 

 restlessly in the sunbeams. They 

 are parasitic insects, and haunt 



the walls for the purpose of depositing their eggs in the larvae of sundry solitary bees 



and wasps. 



Crabro crlbrarlus. 



Philaathus trlangulurn. 



IN the next great division of Hymenopterous insects, the ovipositor of the female 

 is changed into a sharply pointed weapon, popularly called a sting, and connected 

 with a gland in which is secreted a poison closely analogous to that which envenoms 

 a serpent's tooth. These are again divided into the Insectivora, or those which have 

 fore-wings not folded, and the larvae solitary and feeding on other insects; the 

 Sodales, where the fore-wings are not folded, and the larvae are social ; and the Dip- 

 loptera, where the fore-wings are folded, and the larvae (in the social species) inclosed 

 in separate cells. 



The first of these sections comprises all those curious and interesting insects known 

 32 



