While the Integripalpia remained, like the whole order, mainly rheophilic 

 freshwater inhabitants, their larvae not only settled widely in the most 

 diverse biotopes of flowing and stagnant waters, but also spread into the 

 brackish water of lakes and marine coasts, and even 

 in a few cases, into the open littoral of the ocean. 

 '172) ^^fS^SeX-ii .. Life in a portable case changes the whole appearance 



of the larva. Hypognathism develops; the tibiae and 

 tarsi of the hind legs of some forms become gradually 

 longer, developing into characteristic sense organs which 

 are held outside the tube while the body of the larva 

 remains in the tube. With rare exceptions, the tube 

 bearers retain the mesonotal sclerite, and in most forms, 

 also rudiments of the metanotal sclerite. The body, 

 which is covered by the tube, loses to a large extent its 

 mobility and the deep separation of the segments. The 

 segments of tube bearers are separated only by shallow 

 intersegmental grooves; gills and a lateral line appear; 

 the dorsal sclerite of segment 9 is retained in the form 

 of a small sclerite, with rare exceptions. The anal legs 

 are very short; the claw becomes small and simply 

 curved; it functions as a lateral, retaining hook, holding 

 the larva to the inside of the case wall. The larva 

 becomes eruciform. 



The case of most forms (unlike that of Glossosoma- 

 tidae) is differentiated into anterior and posterior ends 

 and tapers gradually posteriorly; the anterior opening 

 is wider than the posterior; the posterior opening is 

 usually covered at the margin with a membrane with a 

 small opening in the middle; this opening is round or of 

 a different form. 



The primitive case of the ancient tube bearers 

 probably resembled the case of the recent Phryga- 

 nopsychidae; these cases are simple, straight, relatively 

 wide tubes with a covering of minute detritus particles 

 (Figure 169), or the larvae make the covering from other 

 remains of animals and plants. The hypothesis that plant 

 material is the primary material for the covering of the 

 primitive structures of the first tube bearers is supported 

 by the fact that the larvae of recent Trichoptera (species 

 of Chaetopteryx, species of Stenophilacini and 

 some species of Limnophilus) use detritus and plant 

 particles in the early stages but begin later to use mineral fragments; the 

 anterior part of the cases of the full-grown larvae of these species consists 

 of mineral particles, while the posterior part, which was built earlier, 

 consists of vegetable particles. The use of detritus particles taken without 

 selection for the covering of the case thus represents the primary method 

 of building the tubular case. The covering of the case is also made without 

 selection by the lst-stage larva of Limnophilus and Phryganea or 

 by the larvae of the species of the preceding families when they are removed 

 from the case and when they renew the lost shelter. The later complication 



FIGURE 169. Larval 

 case of Phrygano- 

 psyche latipen - 

 nis Banks (after 

 Wiggins) 



161 



