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Caddisfly - Trichoptera of Gunnison County, Colorado

Larvae key to Family

Updated 10 June 2008

Under construction! Most families don't have keys yet, many links are to introductions for various families.

1a. Case coiled like a snail shell, constructed of sand grains or small rock fragments. Anal claw comb-shaped.
HELICOPSYCHIDAE: Helicopsyche borealis

1b. Case straight (or slightly curved) or larvae free-living, without a case. Anal claw hook-shaped.

2a. Dorsum of each thoracic segment covered by sclerites.
2b. Metanotum and sometimes mesonotum entirely membranous, or largely so and bearing several pairs of smaller sclerites.

3a. Mature larvae are large 20 mm + in length. Free living, no case, larvae construct fixed retreats under rocks. Abdomen with ventrolateral rows of branched gills; prominent brush of long hairs at base of anal claw. Posterior margin of meso and metanotal plates is lobate.
3b. Very small, mature larvae are less than 6 mm long. Purse shaped case of sand, algae or silk. Abdomen lacking ventrolateral gills. Only one or two hairs at base of anal claw. Posterior margin of meso- and metanotal plates usually straight.

4a. Antennae very long and prominent for a caddisfly, at least 6 times as long as wide. and/or sclerites on mesonotum lightly pigmented except for as pair of dark curved lines on posterior half. Case of sand grains or fine stones.
4b. Antennae of normal length, no more than 3 times as long as wide, or not apparent. Mesonotum never with a pair of dark curved lines.
5a. Mesonotum largely or entirely membranous, or with small sclerites not covering more than half the mesonotum. Pronotum never with an anterolateral lobe.
5b. Mesonotum largely covered by sclerotized plates, variously subdivided and usually pigmented, although sometimes lightly. Pronotum sometimes with a transverse carina terminating in prominent antero lateral lobes.
6a. Abdominal segment IX with sclerite on dorsum.
6b. Abdominal segment IX with membranous dorsum.
7a. Metanotal sa3 usually consisting of a cluster of setae arising from a small rounded sclerite. Prosternal horn present. Mature larvae are among the largest cased larvae in our valley. (Grammotaulius, a Limnephilidae species are bigger.) Case tubular portable case of plant materials, sometimes with a spiral pattern.
PHRYGANIDAE Agrypnia deflata

7b. Metanotal sa3 consisting of a single setae not arisiong from a sclerite. Prosternal horn absent. Case either tortoise-like, made of stones or no case, free living animals.
8a. Basal half or anal proleg broadly joined with segement IX, anal claw with at least one dorsal accessory hook. Case Tortoise-like portable cases of small stones.

8b. Most of anal proleg free from segment IX, anal. Claw without dorsal accessory hooks. No case - free living. Often bright green while alive.
9a. Labrum membranous and T-shaped, often withdrawn from view in preserved specimens. Case Free living with sac-shaped nets of silk.
PHILOPOTAMIDAE Dolophilodes aequalis

9b. I expect more species here - fix this!
10a. Abdominal segment I lacking both dorsal and lateral humps. Each metanotal sa1 usually lacking entirely, or represented by only a single seta without a sclerite. Log cabin-like case, case of fine stones or case of plant materials.
10b. Abdominal segment I always with a lateral hump on each side although not always prominent, with or without a dorsal hump; metanotal sa1 always present, usually with a sclerite bearing several setae but with at least a single setae. Case Various portable cases
11a. Antennae close to anterior margion of eye, median dorsal hump of segment I lacking. Case of plant materials or sand. Often small dark cases in the upper Gunnison Basin.
Lepidostomatidae Lepidostoma Introduction

11b. Antennae about halfway between anterior margin of head capsule and eye. Median dorsal hump always present.
12a. Mesonotum with notch in anteromesal edge.
12b. Mesonotum with anteromesal edge straight.


Wiggins, GB 1996 Larvae of the North American Caddisfly Genera (Trichoptera). 2nd Edition. University of Toronto Press, 457 pages.

Good Links

Key for Pennsylvania - Key to Trichoptera (Caddisflies) of Pennsylvania by Mike Wright (W & J, 1998) http://www.washjeff.edu/Chartiers/chartier/KEY/Trichoptera/trikeytofamily.html

Key for Michigan - Trichoptera - Aquatic Insects of Michigan by Ethan Brighthttp://insects.ummz.lsa.umich.edu/~ethanbr/aim/Keys/Trichoptera/id_tom.html

Brown, Wendy S. 2005 Trichoptera (Caddisflies) of Gunnison County, Colorado, USA