| The Question: What kind of animal builds a 3-4 inches (8-10 cm) high mound of mud balls with a 1 inch (2.5 cm) hole in the top? They look like mini volcanoes. I have found a couple of these in a swampy area near a river. I live in Michigan. Submitted by: Debbie, MI |
The Short Answer: Debbie, that sounds like one of the many species of burrowing crayfish (also called crawfish or crawdads). They dig tunnels down to dampness or even to the water table. And they push up muddy soil out of their burrow into a mini volcano shape, with a neat hole at the top. They’re generally nocturnal, so during the day, all you’ll see are the volcanoes, which can be quite numerous. I have spent most of my life in New England, where I don’t believe any of our native 
crayfish are burrowers. But when I lived in Wisconsin and Kentucky, they were very common. This site has a checklist of the native species of crayfish in Michigan: http://iz.carnegiemnh.org/crayfish/country_pages/state_pages/michigan.htm. There are two burrowers on the Michigan list, the digger crayfish (Fallicambarus fodiens), and the devil crayfish (Cambarus diogenes). The digger crayfish is primarily aquatic, but sometimes digs burrows out of the water. The devil crayfish, however, is a primary burrower, meaning that it lives most of its life in its burrow. So I’m going to guess that’s what you have. For a picture, go to: http://iz.carnegiemnh.org/crayfish/NewAstacidea/species.asp?g=Cambarus&s=diogenes&ssp
More Info: Burrowing seems to be a good strategy for crayfish, as crayfish all over the world have developed a very similar 
lifestyle of digging complex burrows down to damp or wet soil. Like all crayfish, burrowing crayfish have gills in their abdomen under their shell. The gills are capable of gaining oxygen from air instead of water as long as they are wet.
Crayfish, as you might expect, are classified with the clawed lobsters (Nephropidae. There are over 600 species of crayfish, in three main groupings. The Astacidae and Cambaridae are restricted to the northern hemisphere and centered on Asia and North America, respectively. The Parastacidae are distributed throughout South America and Australia. There are no crayfish native to Africa. The Cambaridae are centered on the Southeastern United States, which has the most diverse crayfish assemblage in the world – more than 300 species, a remarkable number when you realize that they seem to occupy very similar ecological niches. There is also an only slightly less impressive collection of crayfish species in Australia. But that part of the world includes some interesting oddballs, including burrowing crayfish that can live far from any surface water. Then there’s the Tasmanian Giant Crayfish, which can reach 4.5 kilograms (10 pounds) – big even by the standards of an ocean-dwelling lobster. To see a picture, go to: http://yhsbiology.wikispaces.com/Crustacea
Trivia #1: The Tasmanian Giant Crayfish (Astacopsis gouldi) is the largest freshwater invertebrate in the world.
Trivia #2: There are two continents with no native crayfish. One is Antarctica. The other is Africa.
The interesting science: It’s easy to understand why Antarctica might not have crayfish. It’s too cold there, and there is no ice-free fresh water. It hasn’t always been that way, and at least one crayfish has been found in Antarctica, so they probably lived there when the continent was located away from the pole. But why are there no native crayfish in Africa? To read more, click here to go to Curious Nature.net, where you’ll find a companion article about the strange distribution of crayfish species around the world.
Well, I should have checked this before I posted on burrowing crayfish, but I just learned that there are in fact burrowing crayfish in the New England states. They are all introduced species from other parts of the U.S., however. Introduced crayfish are a big problem all over the country, with the Rusty Crayfish being the worst culprit. In many areas, this crayfish has displaced all the native species. We should never release crayfish except in the lake or stream from which they came. Releasing bait crayfish is a major contributor to the problem.
I am having a terrible time controlling crayfish in my yard. There are probably 50 burrows and tehy are killing the grass in teh yard In addition they pose a concern for my dog if his paw gets caught in a hole while running. I live in Racine cnty a few hundred yards off the fox river. Any way to get rid of them. I have tried everything.
Thanks
Paul
Paul,
How do you feel about eating crayfish? Some websites suggest pouring various chemicals down their holes. Others say you should never pour any chemicals into the ground, especially not so close to wetlands. I side with the never pouring chemicals into the ground camp.
My suggestion is to make yourself a crayfish trap out of screening and bait it with some kind of meat or fish scraps and see if you can catch enough of them to make a meal. They come out of their tunnels at night to forage, so put the trap out at night. Other than that, the report below mentions that some people believe that mixing gravel into your soil will discourage crayfish.
http://www.usbr.gov/lc/phoenix/biology/azfish/pdf/CrayfishFinal.pdf
What causes blue crayfish abdomen to turn dark or start blackening?
Is this something you have in an aquarium? If so, you might want to check aquarium forums for help from other people who keep crayfish. They would probably have better advice than I could give you.
If you find one should you destroy it
Ed, in general, I’m in favor of learning to live with and adapt to nature, instead of always making it conform to us. And besides that, I have always liked crayfish. So my choice would not be to destroy it. On the other hand, if nature is encroaching on your home and it’s destructive or a danger, then you’ve got to make your own decision. Why are you wanting to get rid of the crayfish?
I have a pond that was built 4 yrs. ago,it will not fill up because the crawfish are digging in the damage and draining it.how do I get rid of them?
I’m not sure what “digging in the damage” means. I’m guessing damage was a bad autofill. But in any event, I don’t know how you get rid of crayfish. I guess youcould call an exterminator. I don’t know how practical it would be to change the type of soil you used around the pond. There are probably some types of soil the crayfish wouldn’t like. Is it made with clay?
They are digging holes in the dam and the water leaks out I have been putting bentonite in the holes and they dig right back through it.
Hmmm … I’m not sure what to tell you. Are you saying that the water is leaking out through the dam because of crayfish holes that go straight through? Or down into the ground? Can you send a picture to tom@tompelletier.com?
We dug the pond in 2012 and while we was digging it the crawfish would dig holes over night. It is 14 ft.deep it fills to 11 ft.and then it starts leaking on the outside bottom of the dam if it fills any higher. I put bentonite in the area I thought was leaking it rained 2 inches that night and the water came up 2 inches. I put more bentonite on the bank it rained another 9 inches it came up 9 inches and started leaking.as the water was going down I noticed a crawfish hole,I dug around in the mud and it swirled down the hole,i filled that hole and the water stopped swirling.i can fill 30 holes a day,go back the next day and be 30 more holes to fill.i set traps and don’t catch anything
Poor in the holes Portland cement. Comes as a powder. Couple scoops in the holes will mix with the water and turn the hole into stone.
Do you have an answer on how to stop them
Hey I think I found an answer to my question moth balls ammonia and bentonite in each hole in filled 170 holes Saturday and on Wednesday only had 15.so that is an improvement. Now I’m going to spread Ortho max and ammonia on the outside of the pond bank
Put a table spoon of lye or an approximately equivalent amount of lye pellets in each hole. The caustic lye kills the crayfish and biodegrades into harmless elements. It’s effective, cheap and bio-friendly.
Hi Brad, thanks for the suggestion. Not sure I could do that, because it seems a tad cruel. Although I have to admit, I’m not sure it’s worse than putting a live lobster in boiling water, which is something I’ve done many times in my life. Tom
Is it true to do nothing to get rid of these critters !
Because of polluting our under the earth water ways.
I have holes I keep covering at my marina. We’re surrounded by water. Been here 12 yrs and 1st time I saw these holes. Now am constantly worried I will step on one or see it. Why haven’t I ever seen one and are they fast? I don’t want to see or step on one EVER
while not native to africa , crayfish do exist in the wild along the banks of lake naivasha in kenya. i lived in kenya between ’83-85′ and recall fishing trips to the lake where i saw numerous large red specimens (about 5″ – relative to the small 1′ beige ones i used to catch in maryland as a kid). in reading this, i happened across another article (written in 2012) detailing how the crayfish is now an invasive species in several african countries.
Have had a few holes surrounded with tiny mud balls around our pond for the last 24 Year’s. This year the whole bank around the pond is filled with these quarter size holes. Never see anything in them, or crayfish in the pond. Not sure whether they are spider or crayfish burrows. But there are so many this year, the bank gives away if you walk too close to the water. And the turtles don’t bask in the sun on the banks now. What are these burrows?
Hi Nancy, where are you located? Can you go out at night, with a flashlight and see if you see anything at the burrows then? With a quarter-sized opening, that close to water, it’s far more likely to be crayfish than spiders. Tom
As one man ask they love clay. I live in North West Ohio an I have the slimest clay in the country. I have them every year and non of the home things work. So far all that works is time. Waiting them out they will go away in a little while. I am trying the lye this year. Someone could make a small $$$$$$$$$$ coming up with a fix.
They live one crayfish in each hole/burrow. Lye can be either sodium hydroxide (NaOH) or potassium hydroxide (KOH). Either formulation simply degrades into its constituent elements that are harmless. It’s not a preventative and has no lasting effect, but it is very effective in that one hole for a short time.
Very nice discussion, just bumped into your site, a good service!
I was looking for info on their burrows, your link:
http://iz.carnegiemnh.org/crayfish/NewAstacidea/species.asp?g=Cambarus&s=diogenes&ssp
is not working,
“We can’t connect to the server at iz.carnegiemnh.org”
at least not this evening.
Find a permanent wet spot in central Illinois, and you’ll find borrows nearby.
Thanks!
Scott
p.s. Loved the badger hole filling behavior!
Hi, Carnegie museum of natural history doesn’t host those pages any more. I’ll have to find a new source when I get a chance. Thanks for letting me know!
Greetings: in part of my yard, there is a natural spring that pretty much makes it miserable to mow. Many years ago there was an abundance of burrowing Crayfish. I believe the Raccoons ate all of the Crayfish. Now we have Coyote’s that have curbed the Raccoon population. How do I re-establish the Crayfish into my yard ? Is there a place that sells burrowing Crayfish that are natural to West Virginia ? Also, on occasion I find a Box Turtle. what can we do to make our yard more accommodating for turtle life ?
I live in Southern Louisiana and we trap crawfishhere as a food delicacy. I happen to live right across the road from a crawfish pond, where they fill the rice land with water and bait the crawfish in a trap. At different times of the year, my yard is covered in about 100-200 crawfish mounds from the crawfish coming from across the country road. This is nothing new to Louisianians. I have came across information that potassium hydroxide poured down the holes should get rid of the burrowing crawdads as we sometimes call them down here. I will be trying this soon, as the mounds dry up in spring and in summer which tears up the lawnmower blades and the deck. Just thought I should share this info
Finally saw the little bugger! He dug under our foundation and is scratching at the solid foam insulation and moving rocks. Very annoying!