Northern Crayfish (Orconectes virilis)

Northern/Virile Crayfish

Orconectes virilis


  • Reddish-brown to olive-brown in colour
  • Bumps on the medial, side of its crarpace (hard shell) and along its chelae (large pincher like claw)
  • Chelae (large pincher like claw) often have dark specs and orange or reddish tips
  • May have paired black marks along its abdomen
  • Can inhabit rivers, streams, lakes, marshes & ponds
  • Prefers waters with rocky substrate, logs, vegetation, rocks, and other debris to use as cover
  • Can survive a temperature range of 0 – 32 celcius
  • Native to Missouri, Mississippi, Ohio, Great Lakes drainages

Consequences of invasion

  • Compete with and displace native crayfish and fish
  • Consume small fish, fish eggs, and tadpoles
  • Reduce the abundance and biodiversity of native snail, macroinvertebrate and macrophyte populations
  • Increase water turbidity
  • Impact irrigation systems and levees as a result of their burrowing near head gates and weir boxes
  • Alter the structure and composition of littoral zones

Introduction and spread

  • Sold in the pet trade as pets and as prey for predaceous aquarium fishes
  • Sold through the bait trade

Integrated pest management options

  • Prevention! Don’t Let it Loose!
  • Protecting sport fish and regulations that reduce their harvest in order to increase predation on northern crayfish in one potential means of reducing their populations