286 



Lange: Lepidoptera 



dashes, separated by a dark brown area, with a luteous 

 and silvery mark below; a marginal, luteous line; a luteous 

 dash at tornus; cilia darker at base. Hind wings with 

 reduced basal, dark area, followed by a reddish-brown 

 band; a median, silvery zigzag line, followed by a grayish, 

 irrorated area; a dark, discal spot; a marginal group of 

 black spots in a yellow field, separated by silvery spots 

 and a marginal group of luteous spots; dark spots pre- 

 ceded at apex and tornus with a thin, interrupted, black 

 line; cilia dark at base. 



Female. — Expanse 16-22 mm. As male, except larger; 

 antennae less ciliate; swimming hairs on meso- and 

 metathoracic legs. 



Male genitalia. — Valva broad, narrowed slightly basally; 

 uncus stout; gnathos strong, curved at tip, with incon- 

 spicuous dorsal spines; aedeagus with 3, externally, 

 basally hinged, groups of spines. 



Female genitalia. — 3ase of ductus bursae wide, purse- 

 like, appearing 3-partitioned; ostium centrally situated; 

 ductus bursae nonsclerotized; bursa copulatrix lacking 

 signum. 



Taxonomic position. — This species is the western 

 counterpart of the eastern fulicalis and related to the 

 northern opulentalis, judging from the genitalia, but 

 is distinct. P. fulicalis (Clemens) extends west as 

 far as Texas, and opulentalis (Lederer) is very com- 

 mon in Canada. 



Distribution. — This is our commonest species in 

 northern California. I have examined it from British 

 Columbia, California, Idaho, Montana, Nevada, Oregon, 

 Washington, and Wyoming. In California specimens 

 have been examined from the following counties: 

 Butte, Colusa, El Dorado, Glenn, Humboldt, Lake, 

 Mendocino, Napa, Nevada, Placer, Plumas, Sacramento, 

 Shasta, Sierra, Sonoma, and Stanislaus. I found this 

 species quite common on the west shore of Rattle- 

 snake Island in Clear Lake, Lake County, and it is 

 associated with fast-flowing streams. The most south- 

 ern locality found by me is the Stanislaus River near 

 Oakdale, but more extensive collecting is needed. 



Biology. — I collected larvae of this species at 

 Trout Creek, Samuel Springs, Napa County, on April 

 11, 1954, and since this initial collection, I have 

 found it quite common in California, Oregon, Washing- 

 ton, and Idaho. It has not been collected to date in 

 the more coastal, acid, cold streams flowing into the 

 ocean. Mr. H. P. Chandler collected this species in 

 many localities in connection with his work with the 

 Department of Fish and Game, and I am indebted for 

 the privilege of examining his collections and includ- 

 ing some of his observations. 



The larvae of this species occur on rocks, often 

 those covered with algae and diatoms, and make 

 silken webs, often in depressions, under which they 

 feed. They also occur occasionally on submerged 

 tree trunks or metal objects in certain situations. 

 Their food consists of algae and diatoms. Often thirty 

 or forty larvae per square foot of rock surface may 

 occur. The larval tents are irregular in outline since 

 they conform to depressions or grooves in rocks. The 

 characteristic cleared areas under the cocoons, which 

 indicate the earlier work of this species, often remain 

 on the rocks after the water level drops. They have a 

 number of small openings around the edge, somewhat 

 like hemstitching, to let in a circulation of water. 



As the larvae enlarge, the tents are extended to 

 enclose more rock surface. When ready to pupate the 

 larva fills in the space beneath the tent with loose, 

 woollike filaments, then spins several blankets of 

 closely matted filaments about itself which are 

 closely appressed and stuck together. The larva spins 

 an anchor to stick the cocoon to the rock, and also 

 to leave openings to let in water. In order to enable 

 its escape from the cocoon the larva cuts a semicir- 

 cular "escape hatch" which is rather inconspicuous 

 but is pushed out flaplike when the adults emerge. 

 The larva then spins an inner, apparently air-tight 

 silken cocoon in which it pupates. The inner cocoon 

 apparently contains air, as reported by Lloyd (1917) 

 for fulicalis. The felty cocoons vary in different 

 streams from 7-15 mm. wide to 15-20 mm. long. 



The mature larvae of truckeealis vary in color from 

 blackish to greenish and have dark brown heads and 

 thoracic shields. They are about 15 mm. long and 

 3 mm. wide (without gills), and the crochets are 

 arranged in a biordinal semicircle. The larvae have 

 characteristic filamentous blood gills, a subspiracular 

 group of three gills on abdominal segments one to 

 six and usually a single supraspiracular gill on each 

 segment. The number of gills varies to a certain extent 

 in different localities and in individuals. The larvae 

 of this species seem to have a wide adaptability to 

 different conditions as they have been collected on 

 small rocks in fast-flowing, shallow riffles, to larger 

 rocks in streams, to bedrock areas of streams in 

 situations where the water is well aerated, to exposed 

 rocks in lakes where the water is aerated. 



The pupa is dark brown, and approximately 2.5 mm. 

 wide at the widest point, by 8 mm. long, and with a 

 characteristic, anchorlike cremaster. The enlarged 

 spiracles on abdominal segments two and three and 

 the ridges on the abdominal segments are similar to 

 those of jaliscalis. Pupae emerge in the laboratory 

 in six to nine days. 



In Rumsey Canyon where the species has been 

 observed throughout the year it is thought that three 

 generations occur. As the water recedes, the old 

 cocoons of earlier generations can be seen, and the 

 fall-collected adults are often very small. Larvae 

 overwinter, and adults disappear during the winter. 

 In the laboratory, adult females were found to crawl 

 down rocks and deposit their eggs under water on the 

 undersides of the rocks. They utilize a plastron type 

 of respiration as the wings are folded back and 

 covered with a silvery sheen. Eggs were found on 

 rocks in many streams, often under several feet of 

 water, and many times in the center of deep holes 

 where it would seem impossible for larvae to crawl. 

 It is assumed that adult females can dive under water 

 and use their swimming legs to reach rocks. There is 

 some indication that the small larvae crawl about, but 

 not to any great extent. Mr. Chandler found larvae on 

 rocks below Pitt 4 Dam, Shasta County, under four 

 to six feet of water, in a part of the stream where no 

 rocks are available for the adults to crawl down, and 

 where the water is very seldom lowered. I found larvae 

 in a fast- flowing section of the North Fork of the 

 American River near Auburn on May 28, 1954, under 



