Aquatic Insects of Michigan

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

Molannidae, Molanna (Hood Casemaker Caddisflies) of Michigan - Identification

Introduction

Two genera of Molannidae occur in North America, Molanna and Molanniodes, of which only the former occurs in Michigan. Ross (1944) provided descriptions of the males of five species to occur in Michigan, and Roy and Harper (1980) described the females of Nearctic Molanna. Schmid (1983) provided a needed detailed update to Ross' descriptions, and also treated females. Larval descriptions for M. blenda, M. tryphena and M. uniophila were given by Sherberger and Wallace (1971), M. blenda, M. ulmerina, and M. uniophila by Morton and Stewart (1996), and M. flavicornis by Wiggins (1996). No one synopsis for the pupae has been published.

The common name (hood casemakers) refers to the distinctive shape and function of the cases that larvae create.

Adults (adapted from Roy and Harper 1980, Schmid 1983)

1a	Males	2
1b	Females	6
2a(1a)	Forewing largely covered with dense brown scales and forming a median longitudinal fold	Molanna blenda Sibley
2b	Forewing without dense covering of brown scales and not median longitudinal fold	3
3a(2b)	a. Hindwing modifed with thin and long arching fold	Molanna ulmerina Navas
	b. Aedeagus generally unmodified, with 3 large, subterminal, apical spines fairly close together, and often with a visible dorsolateral wishbone-like sclerotized marking located roughly one-third the distance from the basal edge
3b	a. Hindwing without such an arching fold	4
	b. Aedeagus not as above
4a	a. Tibiae and tarsi yellowish	Molanna flavicornis Banks
	b. Intermediate appendage of rather regular form, strongly bent ventrally with simple hooks
	c. Aedeagus with a group of 5-6 short anteriorly-directed spines on an enlarged apicoventral-extended endothecal process
4b	a. Tibiae and tarsi dark	5
	b. Intermediate appendage of complex form, with a variously rounded dorsal form, and with a large ventral lobe that is either rounded or acute
	c. Aedeagus not as above, with or without an enlarged endothecal process
5a	a. Lower apicoventral part of intermediate appendage not rounded, forming an acute angle	Molanna tryphena Betten
5b	a. Lower apicoventral part of intermediate appendage not forming an acute angle, rather having a rounded apical form	Molanna uniophila Vorhies
6a(1b)	a. Projection of hind margin of Ab9 tergum absent or vestigial	Molanna flavicornis Banks
	b. Apex of median plate of Ab9 sternum produced into a small quadrate tooth
	c. Maxillary palps somewhat reduced, do not reach level with the third antennal segment
	d. Tibiae and tarsi yellowish
	e. Subgenital plate as in figure
6b	a. Projection of hind margin of Ab9 tergum well developed	7
	b. Apex of median plate of Ab9 sternum produced into a rounded lobe
	c. Maxillary palps longer, reach level with the antennal segment 5 or 6
	d. Tibiae and tarsi darker, brownish
7a(6b)	a. Projection of Ab9 tergum subtriangular, bearing a pair of digitate processes	8
	b. Apex of median plate of Ab9 sternum produced into a large tongue-like lobe which projects far beyond the genital opening
	c. Subgenital plate as in figures
7b	a. Projection of Ab9 tergum quadrate, its apical margin straight or slightly notched	9
	b. Apex of median plate produced into a small rounded lobe
	c. Subgenital plate as in figures
8a(7a)	a. Vaginal plate with sinuate lateral margins and prominent posterior lobes	Molanna ulmerina Navas
	b. Excision of the upper surface subrectangular
8b	a. Vaginal plate smaller, with only slightly curved margins, and without prominent posterior lobes	Molanna uniophila Vorhies
9a(7b)	a. Anterior half of vaginal plate tapering abruptly	Molanna tryphena Betten
	b. Aperture of spermathecal duct elongate
9b	a. Anterior half of vaginal plate large and rounded, not tapering	Molanna blenda Sibley
	b. Aperture of spermathecal duct circular

Larvae
(adapted from Sherberger and Wallace 1971, Moulton and Stewart 1996, Wiggins 1996)

1a	Base of each anal proleg with a long, stout spur	Molanna flavicornis Banks
1b	Base of each anal proleg without such a spur	2
2a(1b)	a. Spinous process on apicoventral margin of each protibia long, at least 5x longer than wide, its basal portion extending well past the tibiotarsal junction	3
	b. larvae construct case generally of fine grains only, without pebbles incorporated into the flange
2b	a. Spinous process on apicoventral margin of each protibia shorter, at most about 3x longer than wide, its basal portion extending short of, or past, the tibiotarsal junction	4
	b. case constructed with fine grains and larger pebbles incorporated along the lateral portions of flange
3a(2a)	a. Apex of base of spine on anterior tibia extending well past the tibiotarsal junction	Molanna blenda Sibley
	b. Membranous area at constriction of frons capitate in mature larvae
3b	a. Apex of base of spine on anterior tibia extending short of, or just past, the tibiotarsal junction	Molanna tryphena Betten
	b. Membranous area at constriction of frons quadrate in mature larvae
4a(2b)	a. Apex of base of spine on anterior tibia extending well past the tibiotarsal junction, and longer than its apical spine	Molanna uniophila Vorhies
	b. Head capsule with a dark, Y-shaped marking follwoing the frontoclypeal and cornal sutures
4b	a. Apex of base of spine on anterior tibia extending well short of the tibiotarsal junction, and shorter than its apical spine	Molanna ulmerina Navas
	b. Head capsule with a dark, U-shaped marking following the frontoclypeal and cornal sutures

References

Moulton SR, Stewart KW. 1996. Caddisflies (Trichoptera) of the interior highlands of North America. The American Entomological Institute, Volume 56. iii + 313 p.
Ross HH. 1944. The Caddis Flies, or Trichoptera, of Illinois. Bulletin of the Illinois Natural History Survey 23(1):1-326.
Schmid F. 1983. Revision des trichoptères canadiens. III. Les Hyalopsychidae, Psychomyiidae, Goeridae, Brachycentridae, Sericostomatidae, Helicopsychidae, Beraeidae, Odontoceridae, Calamoceratidae et Molannidae. Mémoires de la Société Entomologique du Canada 125:1-109.
Sherberger FF, Wallace JB. 1971. Larvae of the southeastern species of Molanna. Journal of the Kansas Entomological Society 44(2):217-224.
Wiggins GB. 1996. Larvae of the North American caddisfly genera (Trichoptera). University of Toronto Press: Toronto, Ontario. 457 pp. + xiii.

Page created: October 23, 2003; Last edited: November 08, 2013 (EB)