In the suborder Annulipalpia (which has campodeiform larvae) the larvae 

 of most families have no gills; the larvae of several genera of the family 

 Hydroptilidae have isolated filiform gills at the end of the body; the larvae 

 of some species of the subfamily Rhyacophilinae and of the families 

 Arctopsychidae and Hydropsychidae have a rich and complex gill apparatus 

 consisting of pectinate, bushlike or tufted forms of simple segmented or 

 branched tracheal gills (Figure 16). In the suborder Integripalpia with 

 eruciform larvae living in portable cases, all species (with a few exceptions) 

 30 have tracheal gills during the later instars; these tracheal gills consist of 

 1-3, rarely 4, filaments; in some groups (family Odontoceridae, genera 

 Leptocerus, Ironoquia, Brachycentrus) and in the Integripalpia 

 there are tufted gills (Figures 17 — 19). 



The abdomen and the two posterior not sclerotized segments of the 

 thorax bear a light pattern of stripes, lines, spots and dots, formed by areas 

 with a thin integument without pigment. During the life of the larva, these 

 parts of the integument are intensely stained with silver nitrate and are 

 the places at which oxygen is absorbed by cutaneous respiration. Krawany 

 therefore called these regions (1935:245) "respiratory fields. " The great 

 physiological importance of cutaneous respiration of the caddis fly larvae 

 may be explained by the disproportion between the oxygen needs of the larva 

 and its ability to satisfy it by the tracheal system. This disproportion is 

 especially marked in large larvae living in cases. 



Anatomy 



Most authors who studied larvae of Trichoptera described only their 

 external morphology; the internal organs were insufficiently studied, and 

 only in a few species. The first, already obsolete description of the anatomy 

 of Trichoptera (including larvae and pupae) was given by Pictet (1834:62—105); 

 a similar description was given by Klapalek (1888:5— 8). In his description 

 of the larva of Molanna cinerea, Betten (1902) also described its 

 internal anatomy; Martynov (1903) studied the peritrophic membrane of the 

 larvae of Agrypnia varia, Phryganea striata and Triaenodes 

 b i c olor; Vorhies (1905:108—118) described the anatomy of the larva of 

 Platyphylax designatus; Lubben (l 907) studied the intestine, the 

 tracheal and the nervous system, the blood gills and genitalia of a number of 

 species of the genera Rhyacophila, Philopotamus, Plectrocnemia, 

 Limnophilus and B r a c hy c e nt r u s, and described the changes in these 

 organs during metamorphosis; Russ (1908) studied the intestine of the larva 

 of Anabolia furcata. Noyes (1915) described the proventriculus of the 

 larva of Hydropsyche; Branch (1922) described the anatomy of the larvae 

 of Hydropsychodes analis, Phryganea inter rupta and Limno- 

 philus indivisus; Brocher (1923) drew attention to the prosternal horn 

 of Phryganeidae and Limnophilidae and its physiological function; Glasgow 

 (1936) gave an anatomical description of the larva of Hydropsyche 

 colonic a. Ahmad (1949) described the mouthparts, the cephalic glands 

 and the intestine of the larva of Hydropsyche sp.; Haller (1948) 

 described the histology of the digestive organs of the larva of Hydro- 

 psyche; Racieqka (1949) gave a detailed anatomical-histological 



26 



