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Guest Column by Christopher Hayes
Ah December, a month marked by holiday cheer, good food, and time spent with loved ones – for better or worse. It’s a season known for warm fires, gifts, travel, and of course…uninvited guests.
I’m not talking about cousin Eddie who drives the RV, or the squirrel hiding away in your Christmas tree. No, I’m talking about the house mouse (Mus musculus), a small rodent who thinks your client’s house (or yours) is the perfect place to escape the cold and find a warm meal!
The house mouse has a long history with humans. It burrowed its way into our homes around 15,000 years ago – right when humans first began to settle down and store food for the winter. They used this new and predictable food source to outcompete other mice, but it also likely contributed to the domestication of cats! Their success has placed mice among the top problems that pest management professionals (PMPs) deal with today, and regardless of their origin, they are here to stay.
The house mouse is responsible for billions of dollars of damage to homes, food loss and public health impacts. Mice can vector diseases to humans, serve as hosts for other disease spreading pests (fleas, mites, lice), and mouse urine contains allergens that trigger allergies and asthma. One survey found that 81% of U.S. homes have detectable mouse allergens in bedrooms (Salo et al. 2018). Even more concerning is that a recent survey of low-income apartments in New Jersey not only found a mouse infestation rate of 20%, but of these infested homes they found that only about half of the residents knew the mice were there (Abbar et al. 2022)! This highlights the importance of your industry, rodent monitoring and surveillance, and on client education and involvement.
So, how do we handle them?
As the expert in rodent control that you are, your first steps should always be monitoring and exclusion – rodent management is easy if they never find their way into the structure. Monitoring can be as simple as placing a glue board just inside the crawlspace door along the wall – just remember to check it! For exclusion, look for areas of potential ingress into the structure you are servicing.
Think like a mouse. They are sneaky, curious, and opportunistic.
Are there holes in crawlspace vents? How about in the siding, where the gas and electrical lines enter the building? What about the chimney? Are there gaps underneath structure entrances and exits? Are there gaps around plumbing pipes and electrical conduits, for example under the sink? All of these represent potential “open doors” for mice and become all the more inviting when temperatures begin to drop, and food becomes scarce outside.
These access points become harder to identify when working in multi-unit housing, so keep an eye out for common signs of mouse activity. Small droppings (1/8-1/4 inch) roughly the size of a grain of rice, with tapered ends, are the most common sign. However, you can also look for signs of chewing on or around entrances and exits to the structure (door sweeps, garage door, crawlspace door), damaged food packaging, or of potential nesting activity.
Despite your best efforts, mice may still find their way into a structure, and we all know what happens when you give a mouse a cookie. There are several control options available to you, ranging from the trusted wooden board snap-trap, various other trap designs (check this guy out!), and the ever-reliable baiting. Use these methods alone or together based on the infestation.
When deploying rodent control measures, it is important to consider the following:
- Are there signs of mouse activity in the area where I am implementing my intervention?
- Does the activity look fresh, or is it possibly old activity?
- Are any non-targets (children, pets, protected species) at risk with my placement?
- Am I deploying rodenticides safely and using a volume appropriate to the level of infestation I am treating?
Other questions may come up based on the account, level of infestation, or hurdles that arise during treatment. Stay tuned as the EPA and U.S. Fish and Wildlife Service continue to assess rodenticides and potential mitigation measures. If you want to learn more, check out our Extension factsheets about mouse biology and behavior and mouse management.
As with all aspects of pest management, North Carolina State University is here to support you and your business! Reach out to me directly with pest management questions, for help with rodent identification, or use this link to sign up for our ride-along program.
Happy Holidays from the NC State Structural Pest Extension, Research & Training Program!
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