Aquatic Insects of Michigan

by Ethan Bright, Museum of Zoology Insect Division and School of Natural Resources and Environment
University of Michigan

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Leptoceridae of Michigan - Identification

[under contruction]: Only a larval key is present; a key to the adults is in preparation


1. Hind tibiae each appearing to be divided into two equal parts - 2
1'. Hind tibiae each not appearing to be divided into two equal parts - 5

2(1). Sclerotized concave plate on each side of anal opening; case cylindrical, constructed of small stones - Setodes
2'. Anal prolegs without sclerotized concave plates; case variable - 3

3(2'). Hind legs without a fringe of swimming hairs; mandibles only slightly assymmetric; case not spirally arranged - Mystacides
3'. Hind legs usually with a fringe of long swimming hairs; mandibles strongly asymmetric; case constructed of spirally arranged pieces of aquatic macrophytes or root tips - 4

4(3'). In dorsal view, head mostly with light brown pigmentation, ending before the occipital foramen; only a small amount of cream ground color visible as a thin smooth crescent between the anterior head pigmentation and occipital foramen - Ylodes
4'. Head pigmentation not as above; dark pigmentation sometimes covering most of the head, but with a broad, irregular cream crescent posteriorly - Triaenodes

5(1'). Middle legs each with a hook-shaped tarsal claw; tarsus curved; case transparent, constructed entirely of silky salivary secretions - Leptocerus
5'. Middle legs each with tarsal claw not as above, curved only slightly; case constructed of various material - 6

6(5'). Maxillary palpi extremely long, extending beyond labrum; mandibles blade-like with a sharp apical tooth - Oecetis
6'. Maxillary palpi not as above, extending little beyond labrum; mandibles short and robust, with teeth grouped around edges of a mesal concavity - 7

7(6'). Mesonotum with a pair of dark curved bars; abdomen short, tapering posteriorly from broad base; gills with several filaments; case short and robust, constructed of various materials; some species found on freshwater sponges - Ceraclea
7'. Mesonotum without a pair of dark curved bars; abdomen long and slender; gills single or absent; case elongate, of various materials, often with atwig extending beyond the end - Nectopsyche

Nectopsyche (larvae, modified from Glover and Floyd, 1996)

1. Two setae present on the metasternum; tracheal gill absent from posterolateral corner of metanotum; also: head with a pattern of dark pigmentaion; case dorsoventrally compressed, and composed of overlapping leaf segments - Nectopsyche pavida (Hagen)
1'. More than two setae present on the metasternum; tracheal gill present or absent from the posterolateral corner of metanotum; case never dorsoventrally compressed - 2

2(1'). Dorsum of head and thorax lacking longitudinal black stripes; also: metasternum with less than 15 setae (usually 8-10); head pattern variable but usually appearing reticulate, without well-defined muscle scars; legs either darkly pigmented or with dark pigmentation at joints - Nectopsyche exquisita (Walker)
2'. Dorsum of head with two conspicuous, longitudinal black stripes, either parallel or forming a V-shaped mark - 3

3(2). Metathoracic legs with well-developed swimming hairs; head and pronotum with parallel, longitudinal, black stripes - Nectopsyche diarina (Ross)
3'. Metathoracic legs without swimming hairs; head with longitudinal black stripes forming a "V"; pronotum lacking strips - Nectopsyche albida (Walker)

Oecetis (larvae, modified from Floyd 1995; larvae of O. ditissa undescribed )

1. Dorsal hump of Ab1 with 4-6 rows of micro-hooks on each side - 2
1'. Dorsal hump of Ab1 without micro-hooks - 3

2(1). Head either yellow, with dark muscle scares or paler yellow, with indistinct muscle scars; ventral apotome approximately 4x wider than long; lotic - Oecetis avara
2'. Head brown to dark yellow, with darker muscle scars; ventral apotome approximately 2x wide as long; lotic - Oecetis disjuncta

3(1'). Postgenal sclerites separated by distinctive brown and pale areas; lateral hump of Ab1 sometimes with a dark, elongate sclerite; also: ventral apotome subrectangular, 4x wider than long, with small posterolateral, triangular sclerites; lateral sclerite of Ab1 light yellow, with 2 ventral setae; metasternum with 2 setae; lotic - Oecetis eddlestoni Ross
3'. Postgenal sclerites not separated by dark and pale areas; shape of lateral sclerite of Ab1 variable - 4

4(3'). Metasternum with 2 setae; swimming hairs present on hind tibiae; hind tarsi longer than trasal claws; case constructed of root or plant fragments placed transversely - 5
4'. Metasternum with >2 setae, often with row of 10 or more; swimming hairs absent on hind tarsi; hind tarsi as short as, or shorter, than tarsal claws; case constructed of sand grains or irregularly-placed plant or detrital pieces - 6

5(4). Head brown with light muscle scars; case constructed either of short twigs or roots (angled "log cabin" appearance), or thin, flat, quadrate, plant fragments; principally lentic, slow-moving lotic waters, on vegetation - Oecetis cinerascens (Hagen)
5'. Head yellow with dark muscle scars; case exterior more rounded and often curved, especially in early instars; lotic, on root mats, woody debris - Oecetis persimilis (Banks)

6(4'). Mesosternum with a pair of irregular dark areas on each side of meson; coronal suture bordered by a row of 3-4 dark muscle scars on each side; left mandible blunt with deep crease running from apical tooth; case constructed of sand grains - Oecetis osteni Milne
6'. Mesosternum without a distinct pair of irregular dark areas; cornoal suture bordered by 0-2 muscle scars; left mandible without a crease; case constructed of plant material or sand grains - 7

7(6'). Dorsum of head with large, dark spot present on each postgenal parietal between eye and frontoclypeal suture, with an additional spot present at the posterior end of the frontoclypeus - 8
7'. Dorsum of head either pale with no distinct markings, or with other combinations of dark muscle scars, spots, or stripes - 9

8(7). Metasternum with a row of 50-90 setae; ventral apotome trapezoidal, roughly 2x wide as long; coxae of legs with 2-4 muscle scars; tergite of Ab9 with 26-30 setae; mostly lentic - Oecetis ochracea (Curtis)
8'. Metasternum with a row of about 26 setae; ventral apotome subrectangular, short, 5x wide as long; coxae of legs without muscle scars; tergite of Ab9 with approximately 10 setae; mostly lentic, but also slow-moving lotic waters - Oecetis immobilis (Hagen)

9(7'). Head and pronotum usually with several light brown muscle scars; case constructed of sand, or rock pieces, with larger ballast stones attached to the sides; lotic and lentic - Oecetis nocturna Ross
9'. Head and pronotum pale, or with various markings; ventral apotome variable; case constructed of sand or plant/detrital pieces; diverse habitats - Oecetis inconspicua complex


Floyd MA. 1995. Larvae of the caddisfly genus Oecetis (Trichoptera: Leptoceridae) in North America. Ohio Biological Survey Bulletin, New Series 10(3). viii + 85 pp.
Glover JB, Floyd MA. 1996.
Preliminary key to eastern Nectopsyche larvae. Handout at the North American Benthological Society Meeting, Kalispell, Montana, June 3-9, 1996. [unpublished].