Trichoptera of Michigan

Introduction

[under construction] This provisional is key based on the literature cited below, and also serves as links for keys to some trichopteran keys for some families as indicated by links within the key or in the navigation frame to the left.

Adults (adapted from Wiggins 1996, Schmid 1998)

1a	a. Very small (length 1-5 mm) and very hairy species with both pairs of wings very narrow, tapered often with very long fringes, especially in hind wings (fringe length about the width of the hindwing)	Hydroptilidae
	b. Mesoscutum lacking setal warts, mesoscutellar setal warts transverse and meeting mesally to form an angulate ridge
	c. Front tibia never with more than single spur
	d. Lateral ocelli close to eye margin or absent
1b	Species without the above combination of characters	2
2a(1b)	Ocelli present	3
2b	Ocelli absent	10
3a(2a)	a. M of hind wings simple, or if 2-branched, then each banch distinct from base, or discoidal cell open at base, RS double, beginning at the base of wing	Uenoidae
	b. Anterior edge of hind wing with row of stout, hooked setae
3b	M of hind wings 2-branched or 3-branched	4
4a(3b)	A of front wings composed of 3 veins reaching the edge of the wing independently	Goeridae, Goera (in part)
4b	A of front wings with 3 confluent branches that form 2 or 3 closed cells	5
5a(4b)	Maxillary palpi 3-segmented	Limnephilidae, Apataniidae, males
5b	Maxillary palpi 4-segmented	Phryganeidae, males
5c	Maxillary palpi 5-segmented	6
6a(5c)	Terminal maxillary palp (segment 5) flexible, usually at least twice as long as preceding segment	Philopotamidae
6b	Terminal maxillary palp similar to others in structure, usually about same length as preceding segment	7
7a(6b)	a. Maxillary palp with segments 1-2 very short and equal in length, segment 5 ending in a point	Rhyacophilidae, Rhyacophila
	b. Discoidal cell in both pairs of wings open
	c. Spurs 3,4,4, fore tibia with a preapical spur
7b	a. Maxillary palp with segments 1 and 2 subglobular, equal or not equal in length but with segment 5 not ending in a point	8
	b. Discoidal cell in front wings closed
	c. Spurs 2,4,4 or 0,4,4 or 2,4,4, fore tibia lacking a preapical spur
8a(7b)	a. Segment 2 of maxillary palpi equal or subequal	Glossosomatidae
	also: Posterior cephalic setal warts oval or round, and widely separated on meson; pronotum with a mesal pair of warts that are well separated
8b	a. Segment 2 of maxillary palpi clearly longer than segment 1	9
	also: Discoidal cell on both wings closed
9a(8b)	Front tibia with 2 or more spurs, middle tibia with 2 preapical spurs, spurs usually 2,4,4	Phryganeidae
9b	Front tibia with a single spur, middle tibia with 0 or 1 preapical spurs, spurs usually 1,2-3,4	Limnephilidae, Apataniidae
10a(2b)	Segment 5 of maxillary palp flagellate, long, flexible (usually) with numerous cross-striae, and different in structure from, and generally much longer than, the preceding segments	11
10b	Segment 5 of maxillary palp not flagellate, similar to the others segments in structure, and usually approximately the same length as preceding segment (segment 4)	14
11a(10a)	a. Long discoidal cell in front wings	Polycentropodidae
	b. Median cell open or closed, beginning apical to the proximal tip of the discoidal cell (fork has a stem)
	c. Maxillary palp segment 3 inserted before apex of segment 2, which is spinose
	also: Foretibia with a preapical spur, or if spur absent (Cernotina), length of basal segment of tarsus less than twice the length of the longer apical spur
11b	a. Short discoidal cell in front wings	12
	b. Median cell closed and beginning basal to proximal tip of discoidal cell (fork has no stem)
	c. Maxillary palp segment 3 inserted at apex of segment 2
12a(11b)	a. Spurs 3,4,4	Dipseudopsidae, Phylocentropus
	b. Antennae of male longer than front wings
12b	a. Spurs 2,4,4	13
	b. Antennae of male shorter than front wings
13a(12b)	a. Thyridial cell on front wings very small, located at the base of the wing, and without contact with the median cell	Psychomyiidae
	b. Hing wings narrower than front wings
	c. F1 absent, with discoidal cell open and the anal area reduced
13b	a. Thyridial cell on front wings large, medianly positioned and in contact with the median cell	Hydropsychidae, Arctopsychidae
	b. Hing wings equal in width or wider than the front wings
	c. F1 almost always present, discoidal cell closed and the anal area well developed
14a(10b)	Discoidal and thyridial cells of front wings absent also: Antennae little, if any, longer than body; middle tibia with 2 preapical spurs	Molannidae, Molanna
14b	Discoidal and thyridial cells of front wings present	15
15a(14b)	Middle tibia without preapical spurs, but with black spines	16
15b	Middle tibiae with preapical spurs, and with or without black spines	20
16a(15a)	a. Antennae very thin, longer than front wings and much longer than body	Leptoceridae
	b. Very long, slender maxillary palpi clothed with dense, erect hairs
	c. Pronotum partially concealed under the mesonotum also: Middle tibia lacking preapical spurs
16b	a. Antennae shorter than front wings	17
	b. Maxillary palpi thicker than above
	c. Pronotum clearly visible from above
17a(16b)	a. Hind wings with basal half of costal margin equipped with hooks and forming a broad costal angle	Helicopsychidae, Helicopsyche borealis (Hagen)
	b. Dorsum of head with posterior setal warts very large, extending from mesal margin of eye to mid-dorsal line and anteriorly to middle of head
17b	a. Hind wings without hooks or costal angel	18
	b. Dorsum of head with posterior setal warts relatively smaller than above, or antennae 1.5x longer than forewing
18a(17b)	a.Front wings with crossvein between R1 and R2	Sericostomatidae
	b. F-1 merges with discoidal cell for a long distance and the Cu2 ends on Cu1b
18b	a. Front wings without a crossvein between R1 and R2+3	Brachycentridae (in part)
	b.F-1 merges with discoidal cell for a short distance, the Cu2 and Cu1b joined by crossveins
19a(15b)	Median cell of crossvein closed, and antenna much longer than the front wings	Calamoceratidae (eastern, not known in or near Michigan)
19b	Median cell of front wings open or absent, antennae shorter than the front wings	Odontoceridae
19c	Median cell of front wings open or absent b. Antennae shorter than front wings	20
20a(19c)	Thyridial or subthyridial cell of front wings broadened at the apex	Goeridae, Goera (in part)
20b	Thyridial or subthyridial cell of front wings not broadened at the apex	22
21a(20b)	a. Spruts 2,4,4 and hairy	Lepidostomatidae
	b. Middle tibia without black spines
20b	a. Spurs 2,3,3 or 2,4,4, and not hairy	Brachycentridae (in part)
	b. Middle tibia with black spines

Pupae (modified from Ross 1944 and Wiggins 1996)

1a	Two pairs of hook plates present on Ab3-5	2
1b	Two pairs of hook plates never present together on each of segments Ab3-5	3
2a(1a)	Very small, < 6 mm also: apex of abdomen membranous, without definite lobes except ventral membranous ones which contain developing genitalic parts; mandibles without teeth or serrations	Hydroptilidae
2b	Larger, > 6 mm	11
3a(1b)	Abdomen lacking lateral fringe, although isolated setal tufts sometimes present	4
3b	Abdomen with lateral fringe, the fringe continuous where present	14
4a(3a)	Mandibles with only a single apical point, althought his is sometimes extended as a slender filament	5
4b	Mandibles with a least one subapical toothlike point more prominent than the others in addition to an apical point	11
5a(4a)	Hook plates on Ab7, frequently also on Ab8	6
5b	Hook plates not extending posteriorly beyond Ab6	10
6a(5a)	Hook plate Vp with 6 or more hooks	7
6b	Hook plate Vp with only 2 or 3 hooks	18
7a(6a)	Hook plates present on Ab2 also: Hooks of plates on Ab2-4 arranged in an arc curved concavely anteriorly	Psychomyiidae
7b	Hook plates absent from Ab2	8
8a(7b)	Anal processes very slender and pointed, frequently hooked apically, Ab8 lacking hook plates	Uenoidae
8b	Anal processes rounded lobes, pair of hook plates usually present on Ab8	9
9a(8b)	Terminal segment of abdomen with 4 bushy processes, 2 apical and 2 basolateral	Dipseudopsidae, Phylocentropus
9b	Terminal segment with only 2 apical bushy processes	Polycentropodidae
10a(5b)	Antennae little, if any, longer than the body, not coiled around anal processes also: Anal processes simple lobes closely appressed along midline, with stout apical bristles longer than processes themselves	Helicopsychidae, Helicopsyche borealis (Hagen)
10b	Antennae much longer than the body, coiled around anal processes	23
11a(2b, 4b)	Abdominal gills present, 2 pairs of hook plates present on Ab3	Hydropsychidae, Arctopsychidae
11b	Abdominal gills absent, 1 or 2 pairs of hook plates on Ab3	12
12a(11b)	One pair of hook plates on Ab4	Philopotamidae
12b	Two paris of hook plates on Ab4	13
13(12b)	Ab8 and/or Ab9 with a pair of small hook plates, and/or 2 patches of long setae at apex of abdomen	Glossosomatidae
13b	Ab8 and 9 lacking hook plates; also: apex of abdoemn lacking patches of setae	Rhyacophilidae
14a(3b)	Lateral fringe of abdomen extending anteriorly from Ab7 or Ab8 to Ab5 or Ab6	15
14b	Lateral fringe of abdomen extending anteriorly from Ab7 or Ab8 to Ab3 or Ab4	21
15a(14a)	Anal processes short or lobate, < 5x longer than wide	16
15b	Anal processes long and slender, > 5x longer than wide	17
16a(15a)	Anterior hook plates longer than wide, or both dimensions approximately the same, and most plates with 2-4 hooks	18
16b	Anterior hook plates wider than long, and usually each with 5 or more hooks	22
17a(15b, 16a)	Anterior hook plates wider than long	Brachycentridae
17b	Anterior hook plates longer than wide, or the two dimensions approximately equal	18
18a(6b, 16b, 17b)	Bristles of labrum usually hooked apically, antenae usually with dorsal tuft of hairs	19
18b	Bristles of labrum never hooked apically, antennae usually with ventrolateral tuft of hairs	20
19a(18a)	a. Anal processes extremely slender at the apex, threadlike and sinuate	Goeridae, Goera
	b. No apical setae on apical processes
19b	a. Anal processes not greatly narrowed at the apex, and not sinuate	Limnephilidae, Apataniidae
	b. Apex of anal processes usually 2-3 apical hairs
20a(18b)	Mesal margin of mandible concave in outline, apex pointed; anterior hook plates with 2 or 3 hooks	Sericostomatidae, Agarodes
20b	Mesal margin of mandible straight in outline, apex usually attenuate; most anterior hook plates with 1 hook	Odontoceridae
21a(14b)	Anal processes short and quadrate, or triangular in dorsal aspect	22
21b	Anal processes long and slender	23
22a(16b, 21a)	a. Ab1 with dorso mesal spined lobe	Phryganeidae
	b. Anal processes in dorsal aspect short and roughly quadrate
22b	a. Ab1 lacking dorsomesal spined lobe	Lepidostomatidae, Lepidostoma
	b. Anal processes more elongate than above in dorsal aspect and roughly triangular
23a(10b, 21b)	a. Anal processes with apical bristles approximately 1/2x long as processes themselves	Molannidae, Molanna
	b. Antennae little longer than body, and not coiled apically
23b	a. Anal processes with much shorter apical bristles, or with none	Leptoceridae
	b. Antennae much longer than body and coiled around base of anal processes

Larvae (adapted from Wiggins 1996a, b)

1a	a. Anal claw comb-shaped	Helicopsychidae, Helicopsyche borealis (Hagen)
	b. Portable case of sand grains resembling a snail shell
1b	a. Anal claw hook-shaped	2
	b. Case not resembling a snail shell, or larvae do not construct a case
2a(1b)	Dorsum of all three thoracic segment largely covered by sclerites	3
2b	First two (pro- and mesonotum) thoracic segments covered by sclerites, metanotum membranous (note: one genus (Ceraclea) of Leptoceridae have lightly pigmented mesonotal sclerites, but with dark curved lines on posterior half)	4
2c	Only the prontoum covered by sclerites, meso- and metanotum membranous	13
3a(2a)	a. Abdomen with ventrolateral rows of branched gills	Hydropsychidae, Arctopsychidae
	b. Anal prolegs, which project freely from the abdomen, with a bursh of many long hairs at the base of the large anal claw
	c. Posterior margin of meso- and metanotal plates lobate
	d. Larvae construct fixed retreats of detritus and rock fragments
3b	a. Abdomen without ventrolateral rows of branched gills	Hydroptilidae
	b. Anal proleg, which does not usually project freely from the abdomen, without a brush of setae, and anal claw very small
	c. Posterior margin of meso- and metanotal plates straight
	d. First three instars free-living, fourth instar larvae construct purse- or barrel-shaped portable cases, or flat silken domes fastened to rocks
4a(2b)	Antennae clong and prominent, at least 6x long as wide, and/or mesonotal sclerotized plates lightly pigmented except for a pair of dark curved lines on the posterior half	Leptoceridae
4b	Antennae much shorter, < 3x long as wide, or not apparent, and mesonotum never with a pair of dark curved lines as above	5
5a(4b)	Metatarsal claw modified to form a short, setose stub	Molannidae, Molanna
	also: Larvae construct portable cases of sand grains with lateral flanges
5b	Metatarsal claw structure not different from those of the other legs	6
6a(5b)	a. Ab1 lacking both dorsal and lateral humps	Brachycentridae
	b. Each metanotal sa1 usually lacking entirely or, if represented only by a single seta without a sclerite
	c. Mesonotal sclerites subdivided
	d. Pronotum divided by a sharp furrow across the middle, area anterior to furrow depressed
6b	a. Ab1 with at least a lateral hump that may not be apparent, dorsal hump present or absent	7
	b. Metanotal sa1 always present, represented by a sclerite bearing at least one (usually more) seta
7a(6b)	Labrum with a transverse row of approximately 16 long setae across the central part	Calamoceratidae (not in Michigan)
	b. Larvae construct case of a hollowed twig, or of leaves and bark variously arranged
7b	Labrum with no more than 6 long setae across the central part	8
8a(7b)	a. Antennae situated at or very close to the anterior margin of the head capsule	9
	b. Prosternal horm absent
	c. Larvae construct cases usually of rock fragments
8b	a. Antennae removed from the anterior margin of the head capsule and approaching the eye	10
	b. prosternal horn present, although sometimes short
	c. Larvae construct cases of rock fragments or plant materials
9a(8a)	a. Anal proleg with a dorsal cluster of approximately 30 or more setae posteomesad of the lateral sclerite	Sericostomatidae
	b. Fore trochantin relatively large, the apex hook-shaped
	c. Larvae construct cases mainly of sand
9b	a. Anal proleg with no more than 3-5 dorsal setae posteromesad of lateral sclerite, sometimes short spines	Odontoceridae
	b. Fore trochantin small, the apex not hook-shaped
	c. Larval case mainly of small rock fragments difficult to crush
10a(8b)	a. Antennae situated close to the anterior margin of the eye	Lepidostomatidae, Lepidostoma
	b. Ab1 without a median dorsal hump
	c. Larvae construct several types of cases, frequently 4-sided
10b	a. Antennae situated approximately halfway between the eye and the anterior margin of the head capsule	11
	b. Ab1 almost always with a median dorsal hump
11a(10b)	a. Mesopleuron modified, usually extended anteriorly as a prominent process	Goeridae, Goera
	also: Mesopleuron occasionally only spinose; Larvae construct small tubular cases with pepples along the side (ballast stones)
11b	a. Mesopleuron, unmodified, not extended as an actue prominent process	12
12a(11b)	Mesonotum with the anteromesal border emarginate, the two primary sclerites closely aligned on the mid-dorsal line	Uenoidae
	also: Larvae construct cases with (ballast) stones arranged linearly along each side
12b	Mesonotum with the anteromesal border not emarginate, though occasionally the two primary sclerites are widely separated on the mid-dorsal line	Limnephilidae, Apataniidae
13a(2c)	Ab9 with a dorsal sclerite	14
13b	Ab9 without a dorsal sclerite	16
14a(13a)	a. Metanotal sa3 usually consisting of a cluster of setae arising from a small rounded or ovoid sclerite	Phryganeidae
	b. Prosternal horn present
	c. Larvae construct tubular portable cases, usually of plant materials
14b	a. Metanotal sa3 consisting of a single seta without a sclerite	15
	b. Prosternal horn absent
	c. Larvae construct cases tortoise-like case of rock fragments, or without a case
15a(14b)	a. Basal half of anal proleg broadly joined with Ab9	Glossosomatidae
	b. Anal claw with at least one dorsal accessory hook
	c. Larvae construct tortoise-like portable cases of rock fragments
15b	a. Most of anal proleg free from Ab9	Rhyacophilidae, Rhyacophila
	b. Anal claw without dorsal accessory hooks, although a secondary lateral claw may be present
	c. Larvae free-living without portable cases, but construct pupal enclosures
	also: Protrochantin conspicuous
16a(13b)	a. Labrum membranous and T-shaped, which often withdraws from view in preserved specimens	Philopotamidae
	b. Larvae construct fixed sac-shaped nets of silk, principally lotic
16b	Labrum sclerotized, rounded and articulated in normal way	17
17a(16b)	a. Trochantin of prothoracic leg broad, hatchet-shaped, separated from episternum by a dark suture line	Psychomyiidae
	b. Larvae construct fixed tubular retreats on rocks and logs
17b	a. Trochantin of prothoracic leg with an acute (pointed) apex, fused completely with the episternum without a separating suture	18
18a(17b)	a. Tarsi of all legs strongly flattened, tibiae shorter than tarsi	Dipseudopsidae, Phylocentropus
	b. Larvae burrow in sandy deposits and construct tubes of sand grains or flattened retreats
18b	a. Tarsi of all legs normal, not flattened, tibiae longer than tarsi	Polycentropodidae
	b.Larvae construct exposed funnel-shaped capture nets or flattened retreats

References

Ross HH. 1944. The Caddis Flies, or Trichoptera, of Illinois. Bulletin of the Illinois Natural History Survey 23(1):1-326.
Schmid F. 1998. The Insects and Arachnids of Canada. Part 7. Genera of the Trichoptera of Canada and Adjoining or Adjacent United States. NRC Research press, Ottawa, Ontario, Canada. 319 pp.
Wiggins GB. 1996a. Trichoptera families, pp. 309-349 in: Merritt RW, Cummins KW, An Introduction to the Aquatic Insects of North America, 3rd Edition. Kendall/Hunt Publishing Company, Dubuque, Iowa. 862 + xiii.
Wiggins GB. 1996b. Larvae of the North American caddisfly genera (Trichoptera). University of Toronto Press, Toronto, Ontario. 457 + xiii.

Page created: May 17, 2003 (EB)
Page last reviewed: November 04, 2003 (EB)