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Key to Trichoptera (Caddisflies) of Pennsylvania

Checklist of Pennsylvanian Trichopterans

Some of these live in cases made out of sticks, gravel or sand. Their antennae can't be seen. They have three pairs of legs and often string like gills found on their abdomen. These larva have hooks on the end of their abdomen. No wings or wing pads present

1a. Case snail-like and made of sand grains (fig. 1); comb-like anal claw (fig. 2) …………………………………………….......................................Helicopsychidae

1b. Case not snail-like nor anal claw as above .....……….................……...............….…..2

2a. Thoracic segments covered only with a single dorsal plate which may have mesal or transverse fracture lines.....................................................…………………………......…3

2b. Metanotum of thorax mostly membranous, possibly having scattered hairs or small plates or divided into 2 or more sclerites ..….........................................................................………4

3a. Gills present in ventral rows on abdomen; no portable case ………......Hydropsychidae

3b. Gills absent from abdomen, which is usually much enlarged (fig. 3); larvae < 5mm long and usually attached to substrate via barrel- or purse-like case ………………….Hydroptilidae

4a. Meso- and Metanotum completely membranous, or with sclerites covering less than half of mesonotum....…………………..................................................................................…5

4b. Meso- and often metanotum with conspicuous scleratized plates; mesonotal plates covering more than half of mesonotum ...................................................................................…..10

5a. Segment 9 of abdomen with dorsum entirely membranous; no portable case ..….......6

5b. Segment 9 of abdomen with dorsum bearing a sclerotized plate; with or without case ..8

6a. Labrum membranous and T-shaped (fig. 4), often withdrawn in preserved specimens; pseudocase a fixed sack-shaped net of silk (fig. 6); muscle scars absent on head ….................................................................................................................Philopotamidae

6b. Labrum sclerotized and widest at base (fig. 5); muscle scars often present on head (fig. 7) ….....................................................................................................................................7

7a. Fore trochantin broad hatchet-shaped, separated from episternum by dark suture line (fig. 8); muscle scars usually lacking on head .......................................................Psycomyiidae

7b. Fore trochantin pointed, fused to episternum, and lacking suture line (fig. 9); muscle scars usually present on head .........................................................................Polycentropodidae

8a. Setal Area 3 (fig. 10) on meso- and metanotum consisting of a cluster of setae (fig. 11); prosternal horn present ......................................................................…..…Phryganeidae

8b. Setal Area 3 on meso- and metanotum consisting of only a single seta (fig. 12); prosternal horn absent …………..……..................................................................................….9

9a. Anal claw about as long as elongate sclerite on anal proleg (fig. 13); conspicuous fore trochantin; case absent .....................................................................…….Rhyacophilidae

9b. Anal claw much shorter than elongate sclerite on anal proleg (fig. 14); obscure fore trochantin; case saddle-shaped or turtlelike (fig. 15) ………………..…Glossosomatidae

10a. Claws of hindlegs shorter than those of middle- and forelegs (fig. 16); case made of sand with lateral projections (fig. 17) …................................................................. Molannidae

10b. Claws of hindlegs as long as those of middle- and fore legs ...........................…..11

11 a. Antennae long and prominent, at least 6 times as long as wide (fig. 18); and/or sclerotized plates on mesonotum lightly pigmented except for pair of dark curved lines on posterior half (fig. 20) …………………………………….…….....……….........….…...Leptoceridae

11b. Anennae short (no more than 3 times as long as wide) and inconspicuous (fig. 19); mesonotum never as above ....................................................................................…....12

12a. Anal proleg with lateral sclerite much reduced in size and produced posteriorly as a lobe around a base of stout apical setae (fig. 21); mesal surface of anal claw membranous at base, with prominent brush of 25-30 fine setae (fig. 22); case of sand grains (fig. 23) .….Beraeidae

12b. Anal proleg with lateral sclerite not produced posteriorly so as to form a lobe around a base of stout apical setae; mesial surface of anal claw largely sclerotized at base and lacking a prominent brush of fine setae........……..……………….…………….................…..13

13a. Labrum with approximately 16 long setae in a transverse row across central part (fig. 24) .………………..….....................................................................………Calamoceratidae

13b. Labrum with fewer than 7 long setae across central part ...........………………...14

14a. No seta or sclerites at SA1 of metanotum (fig. 25); dorsal and lateral humps lacking at segment 1 of abdomen ............................................................................Brachycentridae

14b. Seta and/or sclerites always present at SA1 of metanotum; at least lateral humps present at segment 1 of abdomen .......................................................................…………….15

15a. Antenna situated very close to anterior margin of eye (fig. 26); segment 1 of abdomen lacking a median dorsal hump ………………………………….......…Lepidostomatidae

15b. Antenna situated at least as close to anterior margin of head capsule as to eye (fig. 27), or closer; segment 1 of abdomen almost always having a dorsal hump ...……..…….…..16

16a. Antenna stiuated approximately mid-way between anterior margin of head capsule and eye (fig. 28); prosternal horn present(fig. 30) although sometimes short; chloride epithelia usually present on at least a few abdominal segments(fig. 32) .......………...…..……...17

16b. Antenna situated close to anterior margin of head capsule (fig. 29) ;prosternal horn absent (fig.31); chloride epithelia never present (fig. 33) ...…………………………...……...18

17a. Anterior margin of mesonotum with anteromedian emargination (fig. 34) ....Uenoidae

17b. Anterior margin of mesonotum without anteromedian emargination (fig. 35) ....................................................................................................................Limnephilidae

18a. Dorsum of anal proleg with cluster of approximately 30 or more setae posteromesiad of lateral sclerite (fig. 36); fore trochantin relatively large, the apex hook shaped (fig. 37) .............................................................................................................Sericostomatidae

18b. Dorsum of anal proleg with approximately 5 setae posteromesiad of lateral sclerite, short spines sometimes present; fore trochantin small, the apex not hook shaped(fig. 38) …..............................................................................................................Odontoceridae

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Trichoptera of Pennsylvania