Chilostigma itascae

Geographic Range

The headwaters chilostigman caddisfly Chilostigma itascae was originally found in the Itasca State Park, by the Nicollet Creek, in north central Minnesota, with only ten specimens found from 1974 to 1995 (Houghton, 2017). In 1996, the endemic species was listed as endangered (MNDNR, 1996). Since its listing, this caddisfly has been found at five other sites in northern Minnesota. After finding more specimens the headwaters chilostigman caddisfly the state changed its listing to threatened in 2013 (MNDNR, 2013). This species of caddisfly has not been found in any other state thus far (Houghton and Holzenthal, 2003). (Houghton and Holzenthal, 2003; Houghton, 2017)


The headwaters chilostigman caddisfly has only been discovered as an adult. The first specimen was found by a small, silt-bottomed stream that flows through a wet meadow that contains several spring seeps. The more recently discovered specimen was found in rich spruce swamp and in poor fen habitats that are acid to minerotrophic peatland complex (Houghton, 2017). Adults are also commonly found in an aspen-mixed conifer forest on a ridge adjacent to peatland complex. The adults of headwaters chilostigman caddisflies are commonly seen crawling on snow, where they can be observed mating (Tanida, et al., 1999). (Houghton, 2017; Monson, 1994)

  • Aquatic Biomes
  • benthic
  • rivers and streams
  • temporary pools

Physical Description

Caddisfly species are identified by examining their abdominal processes microscopically. This species has a scoop-shaped median process, that's longer than it is wide (Wiggins, 1975). Adult headwaters chilostigman caddisflies are 8-10 mm in length, with brown wings bearing black hairs (Houghton, 2002). Larvae on the other hand, are unknown to biologist. There has been unidentified larvae found in Itasca State Park that seemed to be good candidates for this species but it is still unknown (Wiggins, 1975). (Houghton, 2002; Wiggins, 1975)

There are two species in the genus Chilostigma, this species and Chilostigma sieboldi. The larvae form of Chilostigma sieboldi is known and could look similar to the headwaters chilostigman caddisfly. Tanida, Nozaki, and Itou (1999), describe Chilostigma sieboldi larvae as 10 –13 mm in length, their color ranges from light to dark brown and sometime even black, they have black mandibles, and small antennae. Their cylindrical larval case is constructed of small pieces of grass and sedge leaves and is up to 13 mm in length. This is what the headwaters chilostigman caddisfly larvae may look like. (Tanida, et al., 1999)

  • Range length
    8 to 10 mm
    0.31 to 0.39 in


Like other trichopterans, the headwaters chilostigman caddisfly is metamorphic. Metamorphic means having an egg, larvae, pupa, and adult stages through out its life (Spellman, 2008). Since no identified larvae have been collected, it is unknown to how larvae mature, or when they mature from larvae to pupae. Adults of this species have been collected from February through March. It is thought that, the emergence activity is strongly dependent on local weather conditions. Winter emergence is very unusual for trichoperans, but the delay could be explained by the larvae maturing in late summer or fall (Houghton, 2002). In the years between 1988 and 1993 a biologist Monson attempted to capture adult headwaters chilostigman caddisflies but was so inconsistent with captures that it is thought that this caddisfly could take several years to develop from a larvae to an adult (Monson, 1994). This species just like other trichopteran species, the adult forms live only a few weeks to mate then die. (Houghton, 2002; Monson, 1994)


Once hatched the headwaters chilostgiman caddisfly is ready to mate. They mate with multiple partners.

Little is known about the headwaters chilostigman caddisfly reproduction behavior, since it has not been observed. It is thought that they reproduce like other trichopterans. The female lays their eggs on the edge of water or by dipping their abdomen into the waters surface (McCafferty, 1981). It is all assumed that their is only one generation per year (McCafferty, 1981). When the pupa mature into a full adult it is considered sexually mature. (McCafferty, 1981)

  • Breeding interval
    The headwaters chilostigman caddisfly are semelparous.
  • Breeding season
    They breed February to March.
  • Range eggs per season
    800 (high)

The adults of this species mate and lay eggs then leave the eggs to hatch. The larvae are self reliant.

  • Parental Investment
  • no parental involvement


It is unknown how long the larvae and pupae stages take place, it could be months or even a year of growth (Houghton, 2017). It is known that the adults emerge sometime between February to March, and live a few weeks like other caddisflies (Houghton, 2017). (Houghton, 2017)


All caddisfly larvae spin silk to make nets to capture food floating in the water or build protective shelters (Wise, 2017). The shelters are attached together with silk to form a case. Caddisflies fly at night and are attracted to light (Wise, 2017). (Wise, 2017)

Home Range

The headwaters chilostigman caddisfly is only found in Northern Minnesota (Houghton, 2017). (Houghton, 2017)

Communication and Perception

Female caddisflies attract males with pheromones (McDade, 2005). Once the males are attracted they either do a visual display to attract the females or they with make sounds with their wings (McDade, 2005).

Food Habits

There is little know about the dietary behaviors of the headwaters chilostigman caddisfly. Other trichopterans commonly consume woody debris and microorganisms, such as, algae it is thought that this species may follow this diet (Wiggins, 1996). (Houghton, 2017)

  • Plant Foods
  • wood, bark, or stems


The headwaters chilostigman caddisfly have many potential predators. Fish and carnivorous invertebrates commonly eat trichopteran larvae and pupae (Wise, 2017). As adults, frogs, birds, and bats are common threats to the adult life form of trichopterans (Wise, 2017). (Wise, 2017)

  • Known Predators
    • Bats, birds, carnivorous invertebrates, fish, and frogs.

Ecosystem Roles

The headwaters chilostigman caddisfly is a great food source to many species, in both terrestrial and aquatic communities (Wise, 2017). The larvae are food sources for fish, carnivorous invertebrates, and waterfowl. The adults are important food sources for bats, birds, and frogs (Wise, 2017). (Wise, 2017)

Economic Importance for Humans: Positive

Larvae and pupae forms are biotic indicators of pollutants (Barbour, et al., 1999). This is extremely important with many freshwater habitats being at risk for degradation (Barbour, et al., 1999).Chironomidae are used for bait with many anglers and are used as models for many fishing lures (Akl, 2013). Caddisfly cases are also sold as art work. Artist Hubert Duprat supplies caddisflies with gold flakes, opal, turquoise, rubies, and pearls to create on of a kind art pieces, the headwaters chilostigman has not yet been used in this manner though (Jobson, 2014). (Akl, 2013; Barbour, et al., 1999; Jobson, 2014)

  • Positive Impacts
  • research and education

Economic Importance for Humans: Negative

There are no known adverse effects of the headwaters chilostigman caddisfly on humans.

Conservation Status

The headwaters chilostigman caddisfly is listed as threatened in Minnesota (MNDNR, 2013). (Minnesota Department of Natural Resources, 2013)


Chelsea Zblewski (author), Minnesota State University Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, Tanya Dewey (editor), University of Michigan-Ann Arbor.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map


uses sound to communicate


Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


mainly lives in water that is not salty.


An animal that eats mainly plants or parts of plants.


A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


active during the night


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


chemicals released into air or water that are detected by and responded to by other animals of the same species


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.


offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.


Living on the ground.


uses sight to communicate


Akl, J. 2013. "Fly-Fishing With Caddis" (On-line). Accessed November 29, 2017 at

Barbour, M., J. Gerritsen, B. Snyder, J. Stribling. 1999. Rapid Bioassessment Protocols for Use in Streams and Wadeable Rivers: Periphyton, Benthic Macroinvertebrates, Fish: Second Edition. EPA, Vol. 2: 1-334.

Houghton, D. 2017. "Chilostigma itascae" (On-line). Department of Natural Resources MN. Accessed October 15, 2017 at


Houghton, D. 2002. BIODIVERSITY OF MINNESOTA CADDISFLIES (INSECTA: TRICHOPTERA). University of Minnesota, 1: 1-194.

Jobson, C. 2014. "Artist Hubert Duprat Collaborates with Caddisfly Larvae as They Build Aquatic Cocoons from Gold and Pearls" (On-line). Accessed November 29, 2017 at

McCafferty, 1981. "Field Guide to Common Texas Insects: Caddisfly" (On-line). Texas A&M AgriLife Extension Service. Accessed November 02, 2017 at

McDade, M. 2005. Grzimek's Student Animal Life Resource, Mammals Volume 1. UXL.

Minnesota Department of Natural Resources, 2013. "Minnesota's List of Endangered, Threatened, and Special Concern Species" (On-line). Minnesota Department of Natural Resources. Accessed October 25, 2017 at

Monson, M. 1994. An Assessment of the Conservation Status of Minnesota Tricoptera. Minnesota Department of Natural Resources, 1: 1-11.


Spellman, F. 2008. Ecology for Nonecologists. Rowman &Littlefield.

Tanida, K., T. Nozaki, M. Itou. 1999. The Larval Stage of Chilostigma sieboldi McLachlan (Trichoptera, Limnephilidae), with Notes on Taxonomy and Distribution. Aquatic Insects, 21(2): 153-160.

Wiggins, G. 1975. Contributions to the systematics of the caddisfly family Limnephilidae (Trichoptera) II.. Canadian Entomologist, 107(3): 325-336.

Wiggins, G. 1996. Larvae of the North American caddisfly genera (Trichoptera). University of Toronto Press, Ontario, Canada., Issue 2: 457.

Wise, K. 2017. "Caddisfly" (On-line). Accessed November 03, 2017 at