Rats (and other rodents)

Download the PDF Facts Sheet Here

A few weeks back, two growers and I were standing in the middle of a squash storage room in mid-construction talking about rodent control.  It brought us back to the excellent presentations by Lisa MacDougall and Hank Bissell at 2015’s VVBGA Postharvest Meeting on rats and rodents. That was great stuff. I thought it would be helpful to reach out to the VVBGA listserv and ask folks what is working for them and what isn’t. I asked for both active measures (traps, rodenticides, FSMA compliant cats and ball pythons, etc.) and passive measures (sealing, doors, packing, hardware cloth, novel construction, accepting the loss, selling everything early).  I also dug up some excellent published references that focus on the issue including two with very detailed guidance on passive exclusion using construction methods.  Here’s my summary.


  1. Cleanliness and Sanitation – Keep food sources well contained and sealed up, reduce “harborage” (places they can hide and live including weeds around edge of building), minimize available standing water. [see Ref’s 4 & 5]
  2. Rodent-Proof Construction – Keep them out of the building. [see Ref’s 1-3 below, some very detailed guidance and novel, passive and relatively inexpensive construction ideas]
  3. Population Reduction – Bait, trap, kill. [see Ref 6 below]


  • Thanks Chris for gathering this information. Very timely as I just found nibbles in some of my stored tomatoes!
  • I think of those talks all the time!  Just found an amazing stash of cover crop seeds… darn those voles(?) are working hard!  Need the answers you compile.
  • I’ve been using that old root cellar at […] all winter for 3 years now without any rodent problems. The process of having someone cement hardware cloth over every crack and crevice was time-consuming but really seems to have worked. I think I finally got rid of the rats in my toolshed through a combination of trapping and disturbing their nesting spots. I’m curious about rodent solutions that apply to the field and high tunnel. I’ve tried to keep cats but the fishers get them.
  • We are a very small pumpkin farm and don’t have the storage needs for food as most of the subscribers, but I will share that I use/reuse lots of snap traps and dump those little, dead vermin bodies while wearing a happy smile!
  • It has only been last winter and this season to date, but I have not had a single animal in the new barn that I built with the 12” concrete knee wall. I have been using covered glue traps to monitor. I partly contribute the success to the fact that I do not set the bins on the ground. They are filled on the trailer and go directly from the trailer to the barn This reduces the chance that a hitchhiker will take a ride into the barn.
  • I just wrote a blog post about this here.  http://michael-kilpatrick.com/reducing-rodent-damage-on-your-farm/
  • We have only killed rats by accidentally moving a pallet onto one. Can’t bait them. They are very intelligent.
  • I have had over 20% of my sweet potatoes damage by voles.  Usually the largest sweet potatoes are the ones half eaten.  The next year I put five “yard windmills” in the sweet potato bed, 100 ft. long, along with a half stick of gum under the black plastic by each plant – cheap gum from the discount food store.  Both were done after I removed the row covers and before the vines spread. That reduced the damage to less than 5%. Very anecdotal and empirical data but worth exploring.  Supposedly the voles do not like vibration of the windmill and eating the gum gives them a bellyache, if fatal I do not know.  Bigger windmills, four inches in diameter and larger, with metal post seem to work better.  How much gum is actually needed I do not know. A SARE  grant in your future.
  • We have a great barn cat and a Jack Russell terrier for our farm. [Included a picture of very cute JRT.]
  • I enjoyed that presentation too. Not the cheapest retrofit, but have had the best luck with making all walls tin or concrete, and having rat traps permanently set at every overhead door jamb, since the seal is not 100%.  Ventilate with in-wall intake and exhaust fans instead of opening doors.
  • Thank you Chris. We are having real problems! Would love to hear of some solutions (organic if that matters…and i think it does).
  • Mice – kernel of corn wedged into mouse trap trigger covered in peanut butter. Rats – same as above but do not the set the trap for several nights and remove all other food sources (in chicken hutch empty all food containers) then set the trap.  Putting a milk crate over the trap prevents chickens, cats , dogs from getting caught.  Also works with chipmunks, and occasionally with red squirrels. Voles – hard to trap, run them down and stomp.
  • I recently tried the tin cats and was happy. Baited them by putting small amount of oats in the trap and tilting it so the grain slid to the end where the screen was. After the mice got a few seed through the screen, they were drawn into the trap to get the remainder. Two mice in the same trap on the first night. The downside is that you have to clean out all the grain each time so it doesn’t hamper the trap mechanism. Have used Contract waxy block in bait stations for at least 4 years. Switching to a different bait because I think they are starting to get  a resistance


  1. Baker R., Bodman G. and Timm, R. Rodent-Proof Construction and Exclusion Methods. 1994. The Handbook: Prevention and Control of Wildlife Damage. Paper 27.  http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1025&context=icwdmhandbook
  2. Hoddenbach, G., Johnson, J., Disalvo, C. Rodent Exclusion Techniques. A Training Guide for National Park Service Employees. 1997. National Park Service. http://www.ehs.ucsb.edu/files/docs/eh/ihrodentexclusion.pdf
  3. Simmons, S. Pest Prevention Construction Guidelines and Practices. CASBO Journal. July/Aug 2005.  http://www.cdpr.ca.gov/docs/pestmgt/pubs/casbo_article.pdf
  4. UMass Extension. Rodent Control on Farms. Fact Sheet – https://ag.umass.edu/sites/ag.umass.edu/files/fact-sheets/pdf/RodentControl08-44.pdf
  5. University of Maryland Extension. Rodent Control on Small Poultry Farms. Fact Sheet. June 2014. https://extension.umd.edu/sites/default/files/_docs/publications/FS-985%20Rodent%20control%20on%20small%20poultry%20farms.pdf
  6. University of Minnesota Extension. Bait Stations for Controlling Rats and Mice. Fact Sheet. http://muextension.missouri.edu/explore/agguidees/wildlife/g09444.htm
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