Orconectes virilis - Northern Crayfish


Information Last Reviewed Spring 2007


The Northern crayfish originated within the North Central United States and has since spread into most of the states, as well as portions of Canada. Presence of this species, outside of its native habitat, has had a negative impact on all aquatic ecosystems it has entered.


Crayfish are especially difficult to identify. For proper identification the specimen needs to be a Form I male or an adult male during the breeding season. Crayfish males can molt or lose their shells after the breeding season and the new shell will look like a juvenile or quasi-juvenile crayfish (Form II male) until tubercles and color patterns appear that make the individuals easier to identify. Because of the difficulty in identifying most crayfish species it is important to go through all of the characters described below, before notifying the authorities about the presence of a possible invasive species. The Carnegie Museum of Natural History has a viable key for identifying most crayfish to genus: (http://iz.carnegiemnh.org/crayfish/Keys/identification.htm)




General Biology

Life Cycle

Habitat Characteristics





Web Sites







Phylum: Arthropoda

Subphylum: Crustacea

Class: Malacostraca

Order: Decapoda

Family: Cambaridae







Juvenile Morphology



Adult O. virilis

 Top Image modified from: http://www.ces.purdeu.edu/extmedia/AS/AS-500.html

 Bottom Image modified from: http://www.mdc.mo.gov/nathis/arthopo/crayfish/varcraw.htm


Adult Morphology


Distinguishing Characteristics 





General Biology












Life Cycle















Habitat Characteristics


Preferred Environment









Water Quality







Native Range


North American Distribution



Probable Means of Introduction
















Control Measures





Literature Cited


  1. Aiken, D.E. 1965. Distribution and ecology of three species of crayfish from New Hampshire. American Midland Naturalist. 73:240-244.


  1. Bergman, D.A. and P.A. Moore. 2003. Field observations of intraspecific agonistic behavior of two crayfish species, Orconectes rusticus and Orconectes virilis, in different habitats. Biological Bulletin. 205:26-35.


  1. Bovbjerg, R.V. 1970. Ecological isolation and competition exclusion in two crayfish (Orconectes virilis and Orconectes immunis). Ecology 51:225-236.


  1. Caldwell, M.J. and R.V. Bovbjerg. 1969. Natural history of the two crayfish of northwestern Iowa, Orconectes virilis and O. immunis. Iowa Academy of Science Proceedings 76:463-472.


  1. Capelli, G.M. and B.L. Munjal. 1982. Aggressive interactions and resource competition in relation to species displacement among crayfish of the genus Orconectes. Journal of Crustacean Biology. 2:486-492


  1. Chambers, P.A., J.M. Hanson, J.M. Burke, and E.E. Prepas. 1990. The impact of the crayfish Orconectes virilis on aquatic macrophytes. Freshwater Biology. 24:81


  1. DiDonato, G.T. and D.M. Lodge. 1993. Species replacements among Orconectes crayfishes in Wisconsin lakes: The role of predation by fish. Canadian Journal of Fisheries and Aquatic Sciences. 50:1484-1488


  1. Dorn, N.J. and G.G. Mittelbach. 2004. Effects of a native crayfish (Orconectes virilis) on the reproductive success and nesting behavior of sunfish (Lepomis spp.). Canadian Journal of Fisheries and Aquatic Sciences 61:2135-2143.


  1. France, R.L. 1984. Comparative tolerance to low pH of three stages of the crayish Orconectes virilis. Canadian Journal of Zoology 62:2360-2363.


  1. Hanson, J.M., P.A. Chambers, and E.E. Prepas. 1990. Selective foraging by the crayfish Orconectes virilis and its impact on macroinvertebrates. Freshwater Biology. 24:69-80


  1. Hazlett, B., D. Rittschof, and D. Rubenstein. 1974. Behavioral biology of the crayfish Orconectes virilis I. Home range. American Midland Naturalist. 92:301-319.


  1. Hill, A.M. and D.M. Lodge. 1994. Diel changes in resource demand: Competition and predation in species replacement among crayfishes. Ecology. 75:2118-2126


  1. Horns, W.H. and J.J. Magnuson. 1981. Crayfish predation on lake trout eggs in Trout Lake, Wisconsin. Rapp. P.-v. Reun. Cons. Int. Explor. Mer. 178:299-303


  1. Lodge, D.M. and Lorman, J.G. 1987. Reductions in submersed macrophyte biomass and species richness by the crayfish Orconectes rusticus. Canadian Journal of Fisheries and Aquatic Sciences. 44:591-597


  1. Lodge, D.M., A.L. Beckel, and J.J. Magnuson. 1985. Lake-bottom tyrant. Natural History. 94:32-37


  1. Lodge, D.M., M.W. Kershner, J.E. Aloi, and A.P. Covich. 1994. Effects of an omnivorous crayfish (Orconectes rusticus) on a freshwater littoral food web. Ecology. 75:1265-1281


  1. Lodge, D.M., C.A. Taylor, D.M. Holdich, J. Skurdal. 2000. Nonindigenous crayfishes threaten North American freshwater biodiversity: Lessons from Europe. Fisheries. 25:7-20


  1. Malley, D.F. 1980. Decreased survival and calcium uptake by the crayfish Orconectes virilis in low pH. Canadian Journal of Fisheries and Aquatic Sciences 37:364-372.


  1. Mirenda, R.J. 1986. Toxicity and accumulation of cadmium in the crayfish, Orconectes virilis. Environmental Contamination and Toxicology 15:401-407.


  1. Momot, W.T. 1967. Population dynamics and productivity of the crayfish, Orconectes virilis, in a marl lake. American Midland Naturalist. 78:55-81.


  1. Peck, S.K. 1985. Effects of aggressive interaction on temperature selection by the crayfish Orconectes virilis. American Midland Naturalist 114:159-167.


  1. Pflieger, W.L. 1996. The Crayfishes of Missouri. Missouri Department of Conservation. Jefferson City, Missouri. 152p


  1. Ruiz, G.M., P. Fofonoff, A.H. Hines, and E. D. Grosholz. 1999. Non-indigenous species as stressors in estuarine and marine communities: Assessing invasion impacts and interactions. Limnology and Oceanography 44:950-972.


  1. Schindler, D.W., and M.A. Turner. 1982. Biological, chemical and physical responses of lakes to experimental acidification. Water, Air and Soil Pollution 18:259-271.


  1. Soderback, B. 1994. Interactions among juveniles of two freshwater crayfish species and a predator fish. Oecologia. 100:229-235.


  1. Wetzel, J.E., W.J. Poly, and J.W. Fetzner Jr. 2004. Morphological and genetic comparisons of golden crayfish, Orconectes luteus, and rusty crayfish, O. rusticus, with range corrections in Iowa and Minnesota. Journal of Crustacean Biology. 24:603-617


Additional Literature


Berrill, M. 1978. Distribution and ecology of crayfish in the Kawartha Lakes region of southern Ontario. Canadian Journal of Zoology. 56:166-177.


Bouchard, R.W. and H.W. Robinson. 1980. An inventory of the decapod crustaceans (crayfishes and shrimps) of Arkansas with a discussion of their habitats. Arkansas Academy of Science Proceedings 34:22-30.


Butler, M.J. and R.A. Stein. 1985. An analysis of the mechanisms governing species replacements in crayfish. Oecologia. 66:168-177.


Capelli, G.M. 1982. Displacement of northern Wisconsin crayfish by Orconectes rusticus (Girard). Limnology and Oceanography. 27:741-745.


Lodge, D.M., T.K. Kratz, and G.M. Capelli. 1986. Long-term dynamics of three crayfish species in Trout Lake, Wisconsin. Canadian Journal of Fisheries and Aquatic Sciences 43:993-998.


Luttenton, M.R., M.J. Horgan, and D.M. Lodge. 1998. Effects of three Orconectes crayfishes on epilithic microalgae: A laboratory experiment. Crustaceana 71:845-855.


Pennak, R.W. 1989. Fresh-water invertebrates of the United States. Protozoa to Mollusca, 3rd ed. John Wiley and Sons, Inc. New York. 628p.


Perry, W.L., J.L. Feder, and D.M. Lodge. 2001. Implications of hybridization between introduced and resident Orconectes crayfishes. Conservation Biology. 15:1656-1666.


Taylor, C.A. 2000. Systematic studies of the Orconectes juvenilis comples (Decapoda: Cambaridae), with descriptions of two new species. Journal of Crustacean Biology 16: 547-551.





Web Sites