Physical Description

From:  Betten, C.  1950.  The genus Pycnopsyche (Trichoptera).  Annals of the Entomological Society of America 43: 508-522.

The species of Pycnopsyche are, as Trichoptera go, fairly common and conspicuous insects of yellow color with some brown markings, from 15 to 23 mm. in length to the wing tips, occurring as adults in August, September, and October, with a few records in July and November. The larvae also are conspicuous among aquatic insects because of their size and in some species because of a slender stick, sometimes two, or even more, which may be laid alongside the wooden case, projecting beyond the rear end. In the pupal case small stones may replace the wood to some extent, the stick at the end may disappear, and the anterior end is fastened to a submerged stone or often to a submerged branch of a tree or shrub. Not many life histories have been described and even the case-building habits of the various species are not fully known. Larvae of either P. lepida or P. subfasciata were observed to have the stick attached when the overall length of the case was but 4 or 5 mm. Larvae of P. gentilis had cases made of pebbles when observed three or four weeks before pupation and very possibly these have stone cases throughout the larval life. Much may depend on what materials are available.


Sometimes ringed darker, basal joint about equal to the head in length. Head covered with numerous yellow hairs and stouter bristles, the latter arranged in areas often referred to as warts. On either side of the head two such spined areas adjacent to the base of the antenna, a larger one parallel with the posterior margin of the head, and a lunate one posteriorly bordering the eye (figs. 4, 5). Prothorax with a large area of coarse bristles on either side; on the mesonotum (fig. 8) narrow areas of bristles extend longitudinally on either side of the scutum and scutellum. Legs each with a line of bristles along the coxa, a black spot prominent on the trochanter, the femur almost bare, tibia and tarsus with numerous black spines, hind tarsus with one or more such spines (P. gentilis frequently an exception). Tibia1 spurs 1-22, 1-3-3, or 1-3-4. Wings with surface more or less tuberculate, their shape varying somewhat with the species (figs. 1, 2). Color of the wings yellow to orange, sometimes almost unicolorous but always with brown areas which, in so far as they are present, conform to a common pattern which may include the posterior apical margin, a series of spots in the bases of the apical cells, a transverse band in the middle of the wing, and, less well marked, the posterior margin. One species has prominent round, brown spots on the forewing; in another species the spots are small and not at all conspicuous. Anal area of the hindwings covered with long thin hairs, the amount of the covering differing with the species, more conspicuous in males than in females. Venation as in the figures (figs. 1, 2), the difference between the species not great.

Eighth tergite of the males fairly heavily sclerotized, its dorsal posterior margin often set with short, black spines, the shape and location of these spinose areas being often diagnostic of the species, lower posterior angle of the chitinous shield of this tergite sometimes extended as a hook, point, or rounded knob (figs. 19, 36, 79). Ninth segment strongly sclerotized, its dorsal half often telescoped into the eighth segment; seen from the side it is widest in the middle, tapering dorsally and ventrally (fig. 61). Attached to the dorsal part of the ninth segment there is a paired structure (10 in figs. 61, 63), representing doubtless the tenth segment, consisting ordinarily of a pair of broad lateral pieces (dorsal or superior appendages of McLachlan and others) running mesally into a pair of processes (intermediate appendages), these often curved at the tips; generally a sclerotized area on the surface of the ninth segment connects the tenth seg1nen.t with the claspers at about the point where the tips of the latter become free, thus the anal aperture is more or less encircled by these structures (fig. 101). Claspers (inferior appendages) in an upright position in relation to the body axis, broadly united to the ninth segment throughout most of their length, the basal part covered with stout bristles; the tips of the claspers, which are free of the ninth segment, variously shaped and often divided (figs. 51, 57, 69, 75). Aedeagus highly characteristic in form, its general structure much the same throughout the genus; arising in a concavity on the dorsal surface are two appendages (titillators) of several types as figured (figs. 13-18).

Female with posterior margin of the seventh ventral segment. Female with posterior margin of the seventh ventral segment bordered with fine hairs (fig. 29). Genital opening at the posterior margin of what appears to be the eighth segment; seen from the side its upper and lower lips are conspicuously protruding, the lower lip forming a subgenital plate which may be rounded, mucronate, or lobed, its appearance differing greatly according to the exact line of vision. Dorsally a terminal segment, perhaps a modified ninth and tenth, is sclerotized, sometimes heavily so; seen from above, its rear margin is in many cases slightly cleft (fig. 23). The anal aperture with its surrounding structures differs considerably with the species, often oval in shape (fig. 41), with varying degrees of sclerotization in its margin; in several species the opening is large, almost rectangular (fig. 31). In well-cleared specimens the outline of the spermatheca may be seen through the body wall (figs. 9-12).

Pycnopsyche gentilis McLachlan
Figs. 9, 17, 67-72
1871. Stenophylax gentilis McLachlan, Jour. Linn. Soc. London, Zool., 11: 108.
1916. Eustenace gentilis Banks, Can. Ent., 48: 122.
1926. Stenophylax gentilis Sibley, Bull. Lloyd Library, No. 27, ,Ent. Ser. 5:107,
218, figs. 100-102, 109.
1934. Stenophylax gentilis Betten, N.Y. State Mus. Bull., 292: 342, pl. 48,
figs. 3, 4.
1943. Pycnopysclze perplexa Banks nec Betten and Mosely, Harvard Mus. Comp.
Zool., Bull., 92: 346, fig. 35.
1944. Pycnopsyche gentilis Ross, Bull. 111. State Nat. Hist. Surv., 23: 299 (listed).

The male of this species is easily recognized by the median scabrous area on the rear margin of the eighth tergite and by the heavy appendages of the aedeagus. The female has the subgenital plate more distinctly trilobed than any other species. The wings of this rather large species are shiny and transparent, the veins of the anastomosis, particularly in its posterior part, are darker than the remainder of the venation and stand out because of the lack of color in the wings. The species is reported from Nova Scotia, New York (Aug. 22-Sept. 28), from most of the northeastern states, Pennsylvania, New Jersey, North Carolina, and Georgia (Oct. 23).


Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

C. Betten

Belongs to 0 communities

This taxon hasn't been featured in any communities yet.

Learn more about Communities


EOL content is automatically assembled from many different content providers. As a result, from time to time you may find pages on EOL that are confusing.

To request an improvement, please leave a comment on the page. Thank you!