House Mouse Control in Single-Family Dwellings

The house mouse has been dubbed by some scientists as the "second most successful mammal on Earth." It also represents the most important rodent pest in the United States, accounting for more than 65 percent of all rodent work performed by pest management professionals, according to some estimates. That’s why it is essential service technicians thoroughly understand how to identify and control this ubiquitous pest, particularly in residential settings which represent one of the industry’s core markets.

WHERE TO START? Servicing single-family dwellings for mice begins by inspecting all areas the client has reported seeing or suspecting mouse activity. Carefully look for signs of mouse activity including fecal pellets, gnawing damage, grease marks, and urine stains and odors. To avoid callbacks, it is important to inspect more than the areas where the client has seen rodent activity and check in all other vulnerable areas.

TRAPPING PROGRAMS. Traps and/or bait stations can be installed in those areas indicating rodent signs. If dogs, cats and young children are present around the home, only traps and trap stations should be installed in mouse-active areas that are prone to possible tampering or investigations by children or pets. In areas not accessible to children and pets, selective baiting also can be done as described below:

For minor mouse infestations, such as one or two mice in the kitchen or garage, six to eight mousetraps can completely eliminate a mouse problem in a couple nights of trapping. Double sets of traps set behind the refrigerator, stove and underneath the sink cabinet often solves the problem (see Figure 1, page 26). Traps can be installed into plastic trap stations for greater professionalism and concealing the carcasses until the mice are collected.

For mouse initials involving more than a few mice, service efficiency will be essential. To be efficient, it is best to err on the side of installing more traps than what is needed. For example, if the inspection has revealed mouse activity in the basement, attic and attached garage, as many as six traps per area, as well as up to six for the kitchen and two for the bathroom will be best. A total of 26 traps! Sometimes this seems like a lot of traps to the homeowner and to some professionals. But eliminating future callbacks is the key to satisfied customers and making a profit on the job. Placing and setting 26 mouse traps does not take much longer than setting only eight to 10 traps.

Plus, erring on the side of installing more traps than is needed makes sense, even for minor infestations. First, the additional traps may catch mice that did not leave many visible signs, and thus were not detected during the inspection. Second, by setting traps throughout the structure the pest management professional is essentially monitoring and "profiling" the entire house. The status of the mouse activity in all areas of the house can then be confidently reported to the client. Such monitoring, in addition to the actual control, is what IPM is all about.

Wherever traps are set, it is best to set double sets. Some mice react to new objects in their runways by jumping over the objects or running around them. The double sets help capture the jumpy mice.

Most human or pet foods are good mouse trap bait. Peanut butter is universal bait and is convenient to carry and store long term in pest management vehicles. Chocolate syrup as squeezed from its container is also effective. Some traps also should be baited with dental floss, string or any stringy, soft items. Pregnant female mice increase their foraging for nesting materials just prior to giving birth and stringy materials appear natural to them as they resemble leaf stems, grass blades, etc. When a pregnant female is captured we are, in fact, capturing a future family of mice. The dental floss is also a great tool to tie pieces of dog or cat food nuggets to traps.

For maximum catch potential, traps should be installed both on active runways and into any dark corners in areas where mouse signs are evident. Corners provide a tactile feedback to the guard hairs of rodents, much the same as the crack and crevice provides to the antennae of a cockroach. Mice gravitate to corners because they literally feel safe in these areas. In areas of the home or apartment where children or pets may be prone to investigating traps, they can be installed inside inexpensive, self-assembling cardboard bait stations or any of the other non-tamper-resistant bait stations.

Multiple-catch traps – wind-up and non-wind-up models – also can be used in residential situations where the infestation is severe or where many mice are active within a small area (e.g., a family of mice active in the cabinets of the garage).

Glue traps also can be used, but the residential program will benefit most if the glue traps are a supplemental tool to snap traps and/or baits. Many adult rodents are able to detect and avoid dangerous sticky surfaces or they are strong enough to escape from them unless they are totally committed to the entire board. Some homeowners also may find the prolonged death associated with glue traps unacceptable. Similar to other rodent control devices, glue traps must be kept out of harms way of pets and children. Glue tray traps should never be installed into a room where a crawling toddler might encounter the trap as this could pose a serious hazard to the child.

BAITING PROGRAMS. Relative to the number of service visits needed to correct a rodent infestation, baiting programs are more efficient than trapping programs. If baits are installed into the high-activity areas of the mice, control can be achieved in both minor and severe infestations relatively quickly and economically with minimal callbacks for the pest management professional. Also, fewer numbers of placements are needed with baits. For example, one or two stations per area may suffice for the average residential mouse infestation. And when bait stations are installed, an ongoing control tool is available for mice in between service visits, whereas once a trap is successful, that trap is no longer available to catch more mice.

The disadvantages to baiting in residential situations include possible odors from the decaying mice and, more important, the safety concern for pets and children in certain households. However, with improvements in tamper-resistant mouse baiting technology and strategic installations based on thorough inspections, the potential for safety risks to non-targets should be minimal.

Currently, there are several tamper-resistant mouse bait stations available that offer site-specific information for baiting in residences and other sensitive environments such as schools. These situations actually provide a level of tamper-resistance, which by their inherent design exceeds some other tamper-resistant bait stations, as well as the tamper-resistant criteria set forth by the EPA. In residential accounts where baiting is necessary, and where children and beloved companion animals are present, such stations fill the ticket.

The success of these ready-to-use tamper-resistant mouse stations and the associated control programs has been very good. There are several reasons for this:

· The plastic molded stations are strong and can withstand the tampering of young children and companion animals. They are highly resistant to crushing and breakage. Some models utilize a lock and key mechanism, enabling only the professional to have access to the bait. Locks and keys also are perceived by the public as providing excellent safety.

· The station design promotes minimal handling time. They come ready to use or involve simply dropping a block into a slot and closing the lid. Some models have see-through inspection plates.

· Because these stations utilize the block bait formulation, the blocks are secured within the stations and cannot be shaken out or carried out by the mice. This significantly minimizes the bait translocation hazard. In heavy infestations, however, blocks may be whittled down to fine particles.

· The block baits employed in these stations are extruded, high-quality grain baits which the mice find very attractive. Moreover, a single 1-ounce block provides enough bait to control six or more mice.

· The compact size of the stations enables them to be installed into various tight spaces favored by mice inside homes. For example, they can be taped easily onto narrow ledges ( e.g., basement sill plates). For mice harboring in hard-to-reach areas such as deer mice nestled into wall voids, fishing line can be threaded through the stations and the stations lowered into voids, or the station can be tossed into other hard-to-reach areas. By attaching the line with a tack, the stations can be retrieved and inspected, rebaited or removed after the program is completed.

· The small size of these stations also enables several stations to be carried in a small box or service kit, eliminating the professional from transporting a lot of equipment into the account. This is especially helpful when baiting high-rise residential accounts.

· The triangular shape of some models enables them to be fitted into corner locations which are attractive feeding and resting areas for mice.

CONCLUSION. Under conducive conditions the house mouse is a prolific breeder, so it’s critical to control this pest sooner rather than later. By conducting a thorough inspection and designing a control program that takes into account the unique behavior of this ubiquitous pest, service technicians will control house mice in single-family dwellings before a serious infestation develops.

The preceding article was excerpted from Bobby Corrigan’s book, Rodent Control: A Practical Guide for Pest Management Professionals. To order a copy of the book, call 800/456-0707 or visit our online book store at www.pctonline.com/store.