182 A BOOK OF INSECTS 



perpendicular burrows in sandy soil, often extending them 

 to a foot or more below the surface. They are whitish, 

 soft-skinned grubs, the head and prothoracic segment being 

 broad and horny. Moreover, the ninth segment is 

 Punch-backed in a remarkable manner, and furnished 

 with two curved hooks, by means of which the larva is 

 able to scramble up or down its burrow, and to support 

 itself just within the entrance, which it blocks up with 

 its broad head and prothorax. In this position it waits 

 patiently until another insect comes within striking 

 distance, when it instantly throws back its head with a 

 rapid jerk and seizes its prey with its strong sickle-shaped 

 mandibles. The victim is then dragged hastily to the 

 bottom of the burrow, and there demolished. 



For some reason not easy to fathom, insects have failed 

 to acquire the art, so marvellously perfected in the case 

 of many spiders, of weaving webs for trapping their prey. 

 The only exceptions are found in a family of caddis-flies 

 known as the Ui/dropsychides. Unlike most of their 

 congeners, the larva? of these insects are carnivorous ; in- 

 stead of constructing portable dwellings, they live in fixed 

 cases made of sand or little pieces of stone fixed together 

 with silk. A Brazilian species, described by Muller, fre- 

 quents the rapids of rivulets, and makes its home upon 

 the upper surface of a stone. The mouth of the case 

 faces up stream, and is provided with a large, funnel- 

 shaped veranda, over which a beautiful silken net is spun. 

 Several of these larva? build their funnels side by side 

 on the same stone, like a row of eel-pots, and in this 

 way intercept any small aquatic creatures which may be 

 brought down by the water. The larva? of an allied North 

 American species have been watched by Dr. Howard, 

 who tells us that in this instance " the tube of the funnel 

 is bent nearly at right angles with the mouth. The mouth 



