494 HYMENOPTERA. 



They may be known by the large folded front pair of wings, and the two bristle-like 

 appendages at the tail. 



QUITTING the Neuroptera, we must give a few lines to another order of insects, the 

 TRICHOPTERA, popularly known by the name of CADDIS-FLIES. 



These insects, of which there are many species, are chiefly remarkable in their larval 

 state, on account of the curious portable habitations which they construct. All anglers 

 are familiar with the Caddis, and the singular variety of form and material employed in 

 the construction of its home. Being a soft, white grub, totally unarmed, and presenting 

 a most delicate morsel to every river-fish, the Caddis is forced to conceal itself in some 

 way from its innumerable foes. For this purpose, it builds around itself a nearly 

 cylindrical tube, open at each end, and composed of substances varying according to the 

 locality and the species. Sometimes these tubes are made wholly of short pieces of 

 stick, laid sometimes side by side, and sometimes in a partly spiral form, something 

 like the wires of the submarine telegraph. Sometimes the tubes are made of sand or 

 little stones, while the deserted shells of the planorbis, and other fresh-water shells, 

 are very common materials. 



More than once I have known the Caddis to affix living shells to its case, and in 

 consequence to be sadly bewildered when it wanted to move in one direction and the 

 fettered shell tried to move in another. Fragments of reeds, patches of dead leaves, 

 straw, seeds, and all kinds of similar substances, are employed for this purpose by the 

 Caddis. In my own collection, I have several specimens where the creature has made 

 use of the opercula once belonging to dead molluscs, and one instance where the Caddis 

 has pressed into its service the chrysalis of some moth that had fallen into the water. 

 In some species, the shape of the tube is precisely like that of the elephant tusk-shell, 

 described on page 403, and is built up of fine sand. I found great numbers of them in 

 a deserted stone quarry in Wiltshire. 



When the larva is about to enter the pupal state, it prepares for the expected change 

 by fixing the tube to some firm object, and spinning a sieve-like net across each extremity, 

 so as to permit water to pass, but to exclude all enemies. There is a regular pattern in 

 this net, and each species seems to have a pattern peculiar to itself. Cases thus pre- 

 pared may be procured near the beds of streams and rivers, where they may be seen 

 anchored to the submerged plants and stones. The reader will not fail to notice the 

 analogy between the moveable tube of these insects and that of the too common clothes- 

 moth. The word Trichoptera signifies hairy-winged, and is given to these insects in 

 allusion to the soft hairs with which the front pair of wings are usually coated. 



WE now come to a vast order of insects, technically called the HYMENOPTERA. In 

 these insects the wings are four in number, transparent, membranous, the veins com- 

 paratively few, and the hinder pair smaller than the others. Their mouth is furnished 

 with powerful horny jaws, and with a tongue guarded by the modified maxillae. The 

 females are armed with a many-valved sting or ovipositor. In this enormous order are 

 included all the bees, wasps, and their kin, the great family of saw-flies, the ichneumons, 

 the gall-flies, and the ants, each single family being so large, and presenting so many 

 points of interest, that an entire volume could be devoted to them with great profit. 

 Our space, however, prohibits us from attempting more than a slight sketch of each 

 family, together with descriptions of a few typical species. Without, therefore, enumerat- 

 ing the various arrangements of this large order, or the characteristics on which they 

 are founded, we will proceed at once to the family of the Tenthredinidae, or Saw-flies, 

 the first in Mr. Westwood's system. 



In this and the next family, the females are furnished with a peculiar ovipositor, 

 composed of several pieces, and which, though connected with a gland secreting an 

 irritant fluid, are not envenomed as in the bees, wasps, and their kin. All these insects 

 are comprised under the general term of Terebrantia, or borers, and fall easily into two 

 large groups, in one of which the abdomen proceeds directly from the thorax, and in the 

 other is connected with the thorax by means of a footstalk. Each of these groups is 

 further subdivided, as will be seen in the course of the following pages. 



