The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Faxonius immunis
Faxonius immunis
(calico crayfish)
Native Transplant

Copyright Info
Faxonius immunis (Hagen, 1870)

Common name: calico crayfish

Synonyms and Other Names: Orconectes immunis (Hagen, 1870), Paper shell crayfish (Smith 2013). Faxonius immunis underwent a reclassification in August 2017, changing the genus of non-cave dwelling Orconectes to Faxonius (Crandall and De Grave 2017).

Taxonomy: available through www.itis.govITIS logo

Identification: The calico crayfish is a plain, grey-green species characterized by a pale zone in the middle of the carapace and abdomen. Their chelipeds (pincers) have orange tips, with the exception of male chelipids that usually display a pale purple tint as breeding regalia (Smith 2013).

Size: 1.7 - 3.5 inches total length (Pflieger, 1987)

Native Range: Lakes Erie, Ontario, Huron, and Southern Lake Michigan, lower Ohio, and upper Mississippi drainages. Massachusetts to Wyoming and Alabama to Ontario, Canada (Hobbs, 1974). 

This species extends as far east as Maine and  Connecticut, and as far west as eastern Colorado and Wyoming. It's northermost range includes southern Manitoba, Ontario and Quebec; It's southermost range extends to Kentucky (Adams et al. 2010).



Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Faxonius immunis are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
CO200120011Upper Yampa
CT198919891New England Region
IA201320131Upper Cedar
NY199619961Lower Hudson
PA196120149Clarion; Conemaugh; Connoquenessing; Lower Monongahela; Middle Allegheny-Redbank; Monongahela; Upper Ohio; Upper Ohio-Wheeling; Upper West Branch Susquehanna
WI198119811Lower St. Croix

Table last updated 6/24/2024

† Populations may not be currently present.

Ecology: Found in shallow ditches and sloughs of medium to large rivers with plenty of aquatic plants and plant debris for cover; mud bottoms with stagnant water; can tolerate high turbidity; a burrower that will move from pond to pond. They are considered a generalist species with a broad ecological niche, however they are not able to colonise fast flowing streams (Adams et al., 2010). Breeding occurs in late summer in New York and eggs are laid in the spring (U.S. Fish and Wildlife Service 2015).

Means of Introduction: Sold as bait; probable bait bucket introduction (U.S. Fish and Wildlife Service 2015). Outside the United states, introduction is unclear; Schrimpf et al. (2013) suggests this species has spread via pet trades as well as bait bucket releases.

Status: Unknown.

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

References: (click for full references)

Adams, S., G. A. Schuster, and C. A. Taylor. 2010. Orconectes immunis. The IUCN Red List of Threatened Species, version 2015.1. Available at: http://www.iucnredlist.org/details/153925/0.

Crandall, K.A. and S. De Grave. 2017. An updated classification of the freshwater crayfishes (Decapoda: Astacidea) of the world, with a complete species list. Journal of Crustacean Biology 37(5):615-653. https://doi.org/10.1093/jcbiol/rux070.

Hobbs, H. H., Jr. 1974. A checklist of the North and Middle American crayfishes (Decpoda: Astacidae and Cambaridae). Smithsonian Institution Press.

Pflieger, W. L. 1987. An Introduction to the crayfish of Missouri. Missouri Dept. of Conservation. Missouri Conservationist.

Rogers, C.D. 2005. Identification manual to the freshwater Crustacea of the western United States and adjacent areas encountered during bioassessment. EcoAnalysts, Incorporated.

Schrimpf, A., C. Chucholl, T. Schmidt, and R. Schultz. 2013. Crayfish plague agent detected in populations of the invasive North American crayfish Orconectes immunis (Hagen, 1870) in the Rhine River, Germany. Aquatic Invasions 8(1):103-109.

Smith, R. 2013. Calico crayfish (Orconectes immunis). Ninnescah life. Witchita State University Ninnescah Biology Field Station, Viola, Kansas.

Taylor, C.A. and G.A. Schuster. 2004. The Crayfishes of Kentucky. Illinois Natural History Survey.

U.S. Fish and Wildlife Service. 2015. Orconectes immunis. Available at: https://www.fws.gov/fisheries/ans/erss/uncertainrisk/Orconectes-immunis-ERSS-June2015.pdf

Author: Hosabettu, M. and W.M. Daniel

Revision Date: 3/20/2024

Citation Information:
Hosabettu, M. and W.M. Daniel, 2024, Faxonius immunis (Hagen, 1870): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=210, Revision Date: 3/20/2024, Access Date: 6/24/2024

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [6/24/2024].

Contact us if you are using data from this site for a publication to make sure the data are being used appropriately and for potential co-authorship if warranted.

For general information and questions about the database, contact Wesley Daniel. For problems and technical issues, contact Matthew Neilson.