Aquatic Insects of Michigan

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

Philopotamidae (Finger-Net Caddisflies) of Michigan - Identification

Adults
(Sources: Armitage 1996, Lago and Harris 1987, Ross 1956 and Schmid 1998)

1a	a. Spurs: 2,4,4	2
	b. Front wing discoidal cell long and ogival
	c. Fork 4 of front wing present
	d. Hind wing with apex of vein 2A free or absent
1b	a. Spurs: 1,4,4	Chimarra, 3 (species determination for males)
	b. Front wing discoidal cell short and wide, its anterior tip thickened
	c. Fork 4 of front wing absent
	d. Hind wing with vein 2A curved up and fusing with 1A to form a large closed cell
2a(1a)	Hind wing with vein 2A atrophied beyond cross vein a2, so that only 1A and 3A reach the hind margin of the wing (2 free anal veins), or wings reduced to tiny scales (overwintering females)	Dolophilodes distinctus (Walker)
2b	Hind wing with vein 2A extending beyond crossvein A2, so that 1A, 2A and 3A reach the hind margin of the wing (3 free anal veins), wings never reduced to tiny scales	Wormaldia moesta (Banks)
3a(1b)	In lateral view, male clasper with apical potion elongate into a narrow, rounded, fingerlike lobe	4
3b	In lateral view, male clasper quadrate or ovate, with no elongation of apical portion	5
4a(3a)	Median projection of Ab9 sternum linear and elongate	Chimarra obscura< (Walker)
4b	Median projection of Ab9 sternum short and triangular, broadened at mid-length; also: dorsal aedeagal rod simple at apex with apices convergent	Chimarra socia (Hagen)
5a(3b)	In caudal view, male claspers with high dorsolateral shoulders, the margin of the dorsomesal process appearing concave or sinuate	Chimarra feria (Ross)
5b	In caudal view, male claspers without shoulders, the margin of the dorsomesal process appearing straight	Chimarra aterrima< Hagen

Pupae (from Ross 1944)

1a	Mandibles with a single, incised cusp below the apical tooth	Chimarra
1b	Mandibles with 2-3 sharp teeth below the apical tooth	2
2a(1b)	Mandibles broad, subapical teeth close together	Dolophilodes distinctus (Walker)
2b	Mandibles narrower, subapical teeth farther apart	Wormaldia moesta (Banks)

Larvae (from Ross 1944, Wiggins 1996)

1a	a. Anterior margin of frontoclypeal apotome with a prominent notch	Chimarra, 2
	b. Coxa of fore leg with a long process arising near the distal end
	c. Venter of head with seta no. 18 located at level of posterior edge of ventral apotome
1b	a. Anterior margin of frontoclypeal apotome usually without a prominent notch, although its margin may be somewhat asymmetrical	5
	b. Coxa of fore leg lacking a long process
	c. Venter of head with seta no. 18 located approximately half-way between the posterior edge of the ventral apotome and the occipital foramen
2a(1a)	Apex of frons bearing a pair of large, rounded lobes	Chimarra obscura (Walker)
2b	Apex of frons bearing smaller, pointed lobes	3
3a(2b)	Basal incision of right mandible very deep	Chimarra socia (Hagen)
3b	Basal incision of right mandible shallow	4
4a(3b)	a. Marginal lobes of frons slightly farther apart	Chimarra feria (Ross)
	b. Basal incision of right mandible more conspicuous
4b	a. Marginal lobes of frons slightly closer together	Chimarra aterrima Hagen
	b. Basal incision of right mandible less conspicuous
5a(1b)	a. Fore trochantin projecting freely anteriorly to form an elongate, finger-like process	Dolophilodes distinctus (Walker)
	b. Venter of head with seta no. 18 approximately the same thickness as the stoutest seta on the dorsum of head
5b	a. Fore trochantin projecting freely only a short distance, thus forming a very short process	Wormaldia moesta (Banks)
	b. Venter of head with seta no. 18 stouter than any seta on the dorsum of head

References

Armitage BJ. 1996. Diagnostic Atlas of the North American Caddisfly Adults I. Philopotamidae. 3rd Edition. The Caddis Press: Hiliard, Ohio. ii + 79 p.
Lago PK, Harris SC. 1987. The Chimarra (Trichoptera: Philopotamidae) of eastern North America with descriptions of three new species. Journal of the New York Entomological Society 95(2):225-251.
Ross HH. 1944. The Caddis Flies, or Trichoptera, of Illinois. Bulletin of the Illinois Natural History Survey 23(1):1-326.
Ross HH. Evolution and Classification of the Mountain Caddisflies. University of Illinois Press: Urbana, Illinois. 401 pp.
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, Canada. 319 p.
Wiggins GB. 1996. Larvae of the North American Caddisfly Genera (Trichoptera), 2nd Edition. University of Toronto Press: Toronto, Ontario. xiii + 457 p.

Page created: September 29, 2003; Page last edited: November 08, 2013 (EB)