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About Stephen Vantassel
Expertise
I can assist the public in responding to all kinds of wildlife related problems in the United States and Canada, including birds, mice, rats, skunks, raccoons, beavers, opossums, voles, moles, chipmunks, woodchucks, pocket gophers, and more. My passion is wildlife damage identification, for if you don't know what animal is causing the problem, you can't begin to resolve it responsibly.

Experience
I was a full time animal damage controller for over 5 years and a part-time animal damage controller for over 10. I have been a volunteer for AllExperts.com for over 5 years under the Pest Control Category, when they graciously created a new category that better suited my experience (I don't answer bug questions). I was a licensed animal controller in both Massachusetts, Connecticut and Nebraska. I presently run the Internet Center for Wildlife Damage Management for the University of Nebraska-Lincoln, http://icwdm.org.

Organizations
National Wildlife Control Operators Association, Community Integrated Pest Management group at the University of Nebraska-Lincoln.

Publications
I have published two books (both revised), The Wildlife Removal Handbook rev. ed. and the Wildlife Damage Inspection Handbook rev. ed. Additionally, I have written articles which have appeared in Wildlife Control Technology Magazine, Fur-Fish & Game, The Trapper, The Fur Taker, The Probe, and others. I have co-authored wildlife related publications for the University of Nebraska-Lincoln Extension program and was responsible for revising the handbook designed for the Pest Controllers looking to obtain their category 14 license.

Education/Credentials
I was a trapper education instructor for the state of Massachusetts, and have attended a variety of conferences and trainings.

Awards and Honors
Certified Wildlife Control Operator

You are here: Experts > Science > Animals/Wildlife > Wildlife Damage Control > mystery critter in the attic

Wildlife Damage Control - mystery critter in the attic

Expert: Stephen Vantassel - 11/6/2009

Question
We live in a wooded area and have had occasional problems with mice in the house, but this fall has been the worst ever. Over the past couple of months, we've found evidence (mouse droppings and several nighttime encounters) of mice in the kitchen, bedroom, and attic. We set out two Tomcat Single Catch Mouse Traps baited with peanut butter, and have caught and released (a couple miles from home) about a dozen small gray mice. Thought we had gotten rid of all of them, but a couple of weeks ago, we began to hear scrabbling sounds in the attic wall. After that, we caught and released two mice in the attic. But on several occasions over the past couple of weeks, the peanut butter bait has been eaten but the traps were empty--sometimes open, sometimes closed; sometimes with mouse trappings, sometimes no droppings at all. Spoke with the people at Tomcat, who were very helpful; they said the trap mechanism can become less sensitive after repeated use and they actually sent us three new traps (one multicatch, two single catch). Well, this morning two of the new small traps are open, but all the peanut butter is gone; no droppings in or around the trap. We don't know what to do at this point. Do we have genius mice up there? Or could there be some other kind of critter up there that is small enough to fit inside the trap but too big to close it? My husband is thinking of setting out kill traps or poison, but I hate to do that. Any suggestions would be greatly appreciated.

Answer
There are a number of things you are doing wrong. First, relocating mice is a BAD idea. House mice are an invasive species. They should be killed, not dumped elsewhere besides it's not humane. Second, you aren't using enough traps. You should be using a couple dozen inside with 4 or more multicatch outside.
More info below. There is a lot of reading you should do to learn how to control mice. It will correct a number of things and help you resolve the problem quickly and in an environmentally responsible way.

Mice

Inspection for mice problems
Learn how to investigate a mouse problem in a structure at http://icwdm.org/Inspection/Default.asp

Exclusion:
Tighten the building. As long as openings aren’t being used by insects or animals larger than mice, secure all of them ¼” or larger with caulk, ¼” sized hardware cloth or flashing. Use caution around weeping vents as they need to remain open to drain water. Use aluminum mosquito netting to stop entry but still allow air and water flow.
Additional info is found at http://icwdm.org/Prevention/Default.asp
Exclusion also includes removal of harborage (piles of stuff and long grass) as well as bird feeders. As food increases so does mouse population.   See also http://www.icwdm.org/handbook/rodents/RodentExclusion.asp for more tips.

Exclusion for grills. All the principles for controlling and preventing mice from entering a structure apply to a grill. Exclusion is your best bet. If that is not possible, then you will need to control the population to prevent mice from reaching the grill. Essentially, you have to tighten the grill so they can't get inside. You will need to be sure that your actions won't interfere with the proper functioning of the grill.
In openings that need airflow, you can use 1/4 inch hardware cloth provided it won't restrict air flow too much. In areas where you don't, you can seal of the holes with stuffit or flashing. or other metal material.
Cleaning the grill thoroughly will also help as it will reduce the attraction of the food.

Repellents:
Don’t waste your time. There are no repellents that have demonstrated effectiveness under real world situations. That includes those silly ultrasonic things that are very good at repelling money from people’s wallets.

Trapping:
Trapping is an excellent for controlling mice provided you use enough traps. Think dozens for a single family ranch house. More if the house is larger. Mice need 21 days to create a new litter of mice. Failure to hammer the population means you will just have a rebound in about 2 months. More information on trapping techniques can be found at the link below. There are a variety of traps on the market. Snap traps work well if properly set. See the pdf page below for images on how to properly set and bait them. Multiple catch and glue boards also work. The key is to use enough. There is no magic here. No quick steps.

Toxicants.
Toxicants are effective in controlling mice but you must 1. follow directions to the letter. 2. understand that NO ONE can promise you where the mice will die. If they tell you the mice will die outdoors looking for water DON’T believe them. We suggest trapping and exclusion and then and only then follow up with toxicants if necessary. For most situations it isn’t necessary if the trapping and exclusion were done properly.

Relocation of mice. DON”T do it. House mice are an invasive species. Kill them. Besides, contrary to popular mythology, relocation is rarely humane. Mice moved to new areas have to 1. find food, 2. find shelter, 3. avoid predators 4. All the while trying to get the lay of the land.   I haven’t even mentioned the trauma of any young that may be abandoned because “momma mouse was relocated somewhere else”. Finally, there is the problem of moving a disease into a new area or a healthy mouse into a diseased area. For more information visit http://www.icwdm.org/wildlife/euthanasia/relocation.asp

House Cats
Don’t bother. There is absolutely no evidence that house cats provide an effective control for mice or other rodents. In fact free roaming house cats are a major environmental menace, killing countless desired species of song birds and other ground rodents. Join the effort to put a stop to free-roaming cats to help protect our valuable and increasingly threatened wildlife species. For more info on the dangers of house cats visit http://icwdm.org/wildlife/housecat.asp

Disease precautions
Read the pdf file below.

Additional information can be found at
http://icwdm.org/wildlife/housemouse.asp
http://www.ianrpubs.unl.edu/epublic/live/g1105/build/g1105.pdf
http://icwdm.org/handbook/rodents/HouseMice.asp

We are always looking for images (if you can safely take them) of wildlife damage to help us in our educational mission. We prefer high resolution, (3 mg or higher). Tips on taking better photos can be found at http://www.icwdm.org/Photos/shootingphotos.asp Send to svantassel2@unl.edu or if your e-mail can’t handle large files upload to http://members.icwdm.org
Username use all caps.     ICWDM
Password (all lower case) guest

Please include permission to use the images and where and when the photos were taken. Month/year is fine as is county or city and state.

Disclaimer: As with any activity, remember that animal damage control comes with its own risks and problems which can include but are not limited to legalities, health threats, and personal liabilities. Be sure to follow all state laws governing wildlife and make sure you have a thorough understanding on how to resolve the animal damage complaint. My advice is only as good as your understanding of me and my understanding of your situation. If you have any questions be sure to write back.

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