Know the Enemy (Third in a Series)

Rusty Crayfish (Orconectes rusticus)


These little critters are virtually everywhere in Wisconsin, but are the most plentiful in Oneida and Vilas Counties.

It may take an expert to distinguish 'rusties' from native species, but the impact is almost surely noticeable.  Rusty crayfish are voracious plant eaters, so a lake may experience a reduction in plant life, reducing cover for fish, spawning grounds and food.  Rusty crayfish have also been known to eat fish eggs.  Fish that normally eat native crayfish, don't like the 'feisty' rusty crayfish.


They are aggressive and displace native crayfish. Rusty crayfish are prolific; females lay from 80-575 eggs!


These little invasives prefer to live in areas with cobble, rocks, logs, or other debris.  For cover, bottom types may be clay, silt, sand, gravel, or rock.


Rusties are so aggressive they may alter the ecosystem of a lake.

This species is so prolific that it has been deemed impossible to eradicate.  Introduction of one female to a body of water in the right conditions may cause an infestation.

How are they best controlled?  Read Fish Predation and Trapping for Rusty Crayfish Control on Plum and Star Lakes: A Commentary by Frank G. Splitt of Vilas County. 


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