Step up inspection efforts for elusive mice

Photo: Dejan Kolar/iStock / Getty Images Plus/Getty Images

Buildings have many voids, nooks and crannies for mice to hide. Don’t give up the fight. Photo: Dejan Kolar/iStock / Getty Images Plus/Getty Images

Question: Dan, I am having repeated mouse issues in a grocery store warehouse. I have sealed up every hole I can find, but they are still getting in. What am I missing?

Mus Hunter

Answer: Dear Hunter, there are a couple of possibilities: Either what you need to find is hidden from view, or what you need to see doesn’t happen while you are there.

Humans are great builders. However, we often build space for unwanted guests while constructing the places we live, work and play. Pests usually find harborage areas behind the human-facing layers of a building or features within a building.

For example, we like to have nicely finished walls in our buildings. However, drywall, paneling and other construction features, like fiberglass-reinforced plastic, create large voids and runways. The larger and more complex the structure is, the greater the number of spaces for pests to enter and live. While you may have sealed all the holes you can find on the outside, you may not be able to see the underground utility penetration that allows mice (or other pests) to sneak in around a loose conduit fitting.

I remember dealing with an issue once where rodents traveled along a broken conduit in an underground void and appeared in the attic. Even a thorough attic inspection did not reveal precisely where the rodents entered, but we found the opening with a lot of sleuthing and a little demolition work. The point is, when you encounter a difficult mouse problem, you have to keep looking, even if it means opening walls.

On the other hand, let’s not forget about items we may find inside the building. Many years ago, I was called in to look at a rat problem in a vast grocery distribution center connected to a grocery store. Getting the rat problem under control was relatively straightforward, but a mouse problem was revealed once the rats were (mostly) gone. The rats lived in the walls and products, but the mice were inside the racking supports. They were hidden from view, safe, and with gaps “just big enough” to allow them to come and go — unseen and nowhere near the control devices. A team of talented and dedicated specialists spent many weeks diligently inspecting and trapping the mice.

Mice are curious, adaptive and mischievous, but they do not just appear out of thin air. Or do they? Another possibility is that introductions occur outside the ways you and your client have anticipated. Let’s say you have eliminated all harborage; you have monitoring devices set in precisely the suitable locations, and the client has the perfect receiving process. There should be no way for a rodent to get in, right?

Wrong. There are two main factors to consider:

  1. Your client may be on board with a robust pest prevention program, but there may be some employees who aren’t. You may have to work with your client to check security cameras to see whether doors are being propped open or other recommendations are being ignored.
  2.  Pests don’t always stay home. Employees or customers may bring pests, even mice, in on personal belongings. Trust me; I saw the client video with a mouse dropping out of a customer’s handbag.

All pests can be challenging, but rodent issues often require us to exercise our intellectual curiosity. Ask questions; open doors. Look in, under and behind, and don’t hesitate to engage the client and ask them to move product, raise equipment or open up walls.

About the Author

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Baldwin is the vice president of technical services for Hawx Pest Control in Tombstone, Ariz. He is also an Editorial Advisory Board member for PMP. He can be reached at

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