TRICHOPTERA. 



707 



FIG. 454. Larva of Phry- 

 ganea fusca (after Pictet). 

 h grasping hooks ; k tra- 

 cheal gills. 



case is closed at both ends. For a time the pupa is quiescent ; then 



a nymph emerges and makes its way through the water to some 



stem. This it ascends, splits its skin and gives' exit to the imago, 



which flies away and pairs. Enoicycla 



has in the female only rudiments of 



wings ; and the hind pair are absent in 



Thamastes. The Trichoptera show 



affinities with the Lepidoptera, and it is 



not improbable that the latter have been 



derived from them. 



This order contains some 500 species, 

 about 150 British forms and as many 

 North American divided into seven 

 families : 



Fam. 1. Phryganeidae. The largest forms. 

 Maxillary palps of male hairy and 4-segmented. 

 Antennae and legs stout. The members of this 

 family inhabit still water. The branchiae of the 

 larvae are filamentous. The larval cases are 

 composed of bits of plants and leaves. They live 

 in temperate regions. Phryganea, Neuronia. 



Fam. 2. Limnophilidae. Fairly large forms. Ocelli present. Maxillary 

 palps of male 3-segmented. There is a great variety in the form of the 

 cases ; Enoicycla passes its larval life amongst damp moss. Apatania is said 

 to be parthenogenetic. 



Fam. 3. Sericostomatidae. Maxillary palps of male 2- or 3-segmented. 

 No ocelli. Larvae chiefly live in streams and form their cases of sand and 

 stones. The genus Helicopsyche forms a spiral case something like a small 

 snail's shell. Sericostoma. 



The following four families have 5-segmented maxillary palps in both 

 sexes : 



Fam. 4. Leptoceridae. Long antennae. Very hairy palps with the last 

 segment flexible and simple. Larvae make straight or curved cases of 

 sand. The branchiae are short tufts. They resemble the Tineid moth 

 Adela. Odontocerum is British. 



Fam. 5. Hydropsychidae. Rather hairy palps with the last segment 

 long and jointed. The larvae inhabit streams and make fixed cases, at 

 the entrance to which some species, e.g. Rhyacophylax and Hydropsyche 

 spin silken nets to entrap the insects on which they feed. The larvae of 

 British species of Philopotamus and of Tinodes are said to be without 

 branchiae. 



Fam. 6. Rhyacophilidae. Palps with very few hairs, the last segment 

 simple and cylindrical. Some larvae of this family have no branchiae and 

 breathe by stigmata. They live in rapid streams and make fixed cases 

 under stones. Bhyacophila. 



Fam. 7. Hydroptilidae. Small forms very like Tineid moths. Wings 

 narrow. The larvae make small seed-like cases, and they have no branchiae . 

 Cxyethira fastens its case to leaves of water-lilies. Hydroptila. 



