The Bug Doctor: Adam Villareal, owner and president of Insight Pest Solutions, entomology nerd, and family man. To help demystify the world of bugs, the Bug Doctor answers your questions during our weekly “Ask the Bug Dr.” blog feature. You can submit your bug and pest control inquiries for him on our Facebook page, by tweeting @insightpest, or commenting below.
If you hear little feet scurrying across the floor, come across droppings, or notice damage to stored food, you might have mice in your home. Mice are sneaky and destructive creatures who do most of their foraging overnight, but they leave plenty of clues that make their presence known.
Photo credit: Duncan Hill
Mouse Identification & Inspection
Mouse Identification – Physical Appearance
Mice are gray or brown, with little eyes and large ears. An adult is about 5 ½ to 7 ½ inches long, including a tail that is typically three to four inches long. The life span of a mouse is about nine to 12 months. They produce 6-10 litters a year. House mice will nibble on all types of food, but favor seeds and insects. They are proficient climbers, are color blind and unable to see clearly beyond six inches.
Differences between Mice & Rats
So, how can you tell if a rodent is a mouse or a rat? Fully grown rats are larger than the common house mouse. Young rats have large heads and feet in proportion to their bodies, while adult mice have heads and feet that are proportionally smaller. And, while both rodents gnaw on wood, rats leave behind larger tooth marks. Because house mice are small, they can find their way inside structures easier than rats, making mouse infestations much more typical than rat infestations.
An adult house mouse is typically smaller than an adult rat.
Causes & Signs of Mouse Infestation
House mice can squeeze through very small openings, smaller than a dime. They seek food, warmth and shelter in homes in the fall. You may suspect a mouse infestation if:
You notice a musky odor
You see droppings that are ⅛ to an ½ inch long with pointed ends
You hear squeaking, gnawing or scurrying
You find mouse nests (probably made of shredded paper, insulation, or other material) in sheltered locations such as behind or under furniture and appliances.
Damage from a Mouse Infestation
Mice can contaminate or damage your food, clothing, furniture, books and other items with their droppings. They also may chew through electrical wiring, creating a fire hazard. Bacteria that causes food poisoning can spread through mice if infected feces come into contact with your food. They can also bring fleas, mites, ticks and lice into your home.
Steps To Get Rid of Mice In Your House
Exclusion – Rodent Proofing
This is the most important part of any mice control program. Exclusion means physically blocking the mice from accessing the home. Even if the mice are already inside, this in an important step in long-term control of the mice.
Seal all possible entry points. Mice can get through a space as small as ¼ inch in diameter; that’s the diameter of a #2 pencil. Slowly walk around the perimeter of your home and shove steel wool into any crevices that seem like access points. Nineteen gauge or higher steel wool often works best. Be sure to plug any small holes around utility lines entering the home. Shove enough steel wool into a hole that a mouse won’t bother trying to pull it out.
Install garage door seals to help eliminate an easy entry point.
Keep your grass and other vegetation cut. This helps to remove protected area that mice will use to hide from predators as they attempt to gain entry to your home.
Store wood piles 20 feet or more from your home and never directly against the foundation. Mice will use this as shelter in the warmer months and then more easily move from there to your home in colder weather.
Photo Credit: Armor Pest
Now that the house is sealed up from further rodent entry, you will need to trap or bait for the mice inside the home. Either way, your goal is to convince the mice to consume a bait…so you must limit their access to other food sources in the home. Mice will quickly take advantage of any food source. If you have pets, be sure to only put out the amount of food your pets will eat. Never leave food out overnight.
After exclusion has been performed, trapping works best for mice. Baits are slow to work and can be dangerous to people, pets and wildlife.
Snap traps can catch one mouse at a time, and depending on the size of the infestation, may require frequent resets.
How to set up a mouse snap trap:
Find and prep the right location. Clean up any droppings and remove other food sources such as pet food, grains, crumbs, etc. If food is plentiful, mice may not be interested in your bait.
Smear a small amount of peanut butter on the trigger plate of the trap (peanut butter isn’t the only successful bait, but it’s very good and found in most homes).
Set the trap. There are several types of snap traps, so just follow the instructions that came with the trap. Here’s a helpful 1 minute video.
Carefully place the trap with the trigger along a wall. This puts the bait right in the path of the mouse.
Photo Credit: University of Nebraska-Lincoln
When you have caught a mouse on a snap trap:
Don’t throw away or clean the trap
Drop the dead mouse into a bag and place this in an outdoor trash can
Add bait to the trap if needed
Reset the used trap to catch other mice that may be in the area
Mice will be strongly attracted to a used trap that has the scent of another mouse. Although this trap is used and likely to be quite dirty, it is your new silver bullet for catching any remaining mice.
Glue boards use the natural curiosity of the mice to capture multiple mice on one trap. When one mouse is trapped, other mice will come to investigate and become trapped as well. Placing the traps behind furniture and directly against walls works best since mice mostly travel against walls and under furniture to avoid detection. If the mice have been eating your food, use a small amount of what they have eaten to place in the middle of traps.
There are also traps referred to as humane traps that trap multiple mice and then the mice can be released. This can be an effective solution when good exclusion has been obtained so the mice cannot re-enter your home.
In some circumstances, baiting may be used, but is not recommended as a DIY control method to be used by homeowners due to its increased risk to people, pets and wildlife. Bait use should always be the last consideration for mice control, and should only be done by qualified pest management professionals.
Photo Credit: PEST WEB
Types of Mice
Learn about some common mice you can find in your home. For more information on common residential rodents, go to our pest learning center.
House mice breed rapidly and adapt quickly to changing conditions. This common rodent feeds on seeds, fruits, insects, dog food, grains, and other human food. House mice are known as quick runners, climbers, jumpers and swimmers, but rarely travel more than 50 feet from their shelters.
- Length: Body- 2 1/2″ – 3 3/4″
- Region Found: Throughout the United States
- Residential Location: They nest in dark and secluded areas, often build nests in paper products, clutter, insulation, and fabrics. They like to live in and around structures for convenient shelter and access to food.
- Random/Interesting Fact: Mice are color blind and females give birth to an average of six babies up to six times a year.
- Identification: Mice are usually a dusty gray color with a cream colored belly
Photo credit: liesvanrompaey
Deer mice are nocturnal creatures that generally live in rural areas with a lot of vegetation. They tend to make their nests out of plant material and live in individual home ranges. Deer mice are very active throughout the year. Their feet are modified for running and climbing.
- Length: Body: 2″ – 13″, Tail: 1 1/2” – 9”
- Region Found: Throughout North America – from Panama to Alaska and Northern Canada
- Residential Location: While they prefer rural areas such as fence posts and log piles, they often wander inside garages and outdoor sheds during the winter months.
- Random/Interesting Fact: Deer mice are often used in laboratory experiments as they are generally clean and easy to care for.
- Identification: Deer mice have prominent ears and long tails. Their tails are often half white and half brown. Males often weigh more and are longer than females.
*UPDATE* We invested a lot into creating this comprehensive pest control website resource, featuring lots of suggestions from experts regarding rodent control for homeowners.
Do you have a question about bugs or pest control? We’d love to hear from you. Let us know on our Facebook page, in the comment section below, or by tweeting @insightpest. You may see the Bug Doctor’s answer to your question in a future post.
Posted in: Ask the Bug Doctor