170 NEUROPTERA AND ALLIES 



be distinguished from the lepidopteroiis larvse which have, 

 as a rule, only five pairs. 



The species of Jlitfacus are somewhat common, usually 

 found in woodland, and have some resemblances to the 

 crane flies, but are easily distinguished by the presence of 

 four wings. The genus Bore us is remarkable for appearing 

 in the winter time and occurring in great numbers on the 

 surface of snow. 



Order TRICHOPTERA (Caddice Flies). 



This order is of particular interest scientifically because 

 it appears to be the primitive group from which the order 

 Lepidoptera has been derived. The mouth parts are man- 

 dibulate, the metamorphosis is distinct, the larval forms 

 caterpillar-like but all the species are aquatic and show 

 distinct specialization for aquatic existence. In the adults 

 the body and wings are covered wdth minute flattened or 

 scale-like appendages which approach the condition found 

 in the Lepidoptera and except for the mandibulate mouth 

 parts the group may be considered as distinctly connected 

 with the Lepidoptera. In some forms the wings are opaque 

 and the general appearance is extremely like some of the 

 minute moths. 



Perhaps the most notable feature in the group is the 

 larval habit of forming cases or tubes within which they live. 

 These cases are made of a variety of materials, in some 

 species from minute pebbles, minute mollusk shells, and in 

 many cases with fragments of aquatic plants or various kinds 

 of debris occurring in the water. The cases are constructed 

 shortly after the larvse hatch and are enlarged with the 

 growth of the insect. The head and thoracic legs are 

 projected from the tube, and the tube moved around by its 

 adherence to the posterior part of the body. Some species 

 have a habit of making delicate nets or traps in the water 

 by means of which they catch aquatic animals for food, 

 but in most of the species the larvaj travel around freely and 

 feed upon aquatic vegetation. The tubes or caddices formed 



