[Vertebrate Pests]

A Profile of Inner-City Mouse Populations

House mouse infestations in high-rise apartments and condos in inner-city areas are substantially different from the mouse infestations of suburban developments. In those parts of our cities where house mouse populations are well established, the number of city mice is likely to be large and they are likely spread across city blocks.

THE CAUSES. What factors render inner city areas so vulnerable to chronic, perpetual mouse infestations? First, in all probability city mice have been established since the earliest days of the city itself. Many of the mice we are attempting to control today are descendants of mouse populations stretching way back. Second, inner-city areas are enormously complex structural environments. Consider the three dimensional resource availability of the small mouse relative to nesting zones, protection from predators, foods, and the hidden travel ways among the structural risers, and the various vertical and horizontal plumbing, heating, and electrical chases. After cities are built most of the buildings, sooner or later undergo structural renovations, remodeling, add-ons, and so forth. So too will most of the city’s infrastructure (sewers, utility systems, roadways, etc.). As a result, we create thousands of harborage spaces for city rodents, most of which remain relatively inaccessible to us.

Because mice periodically travel seeking new harborages via many secretive travel pathways available to them, the immigration potential of the mouse into un-infested apartments and office complexes can be substantial. Thus, mice tend to periodically "sprout up" like weeds in one apartment or another.

Recognizing and understanding this city house mouse profile is important for two reasons. First, it has ramifications in the study of the city mouse relative to disease transmission. And second, long-term control of mouse populations in city environments requires a proactive and comprehensive program. Unfortunately, typical mouse control programs in city apartments, office complexes, restaurants, and other city buildings tends to be reactive approaches of installing a trap or two, or some bait when a mouse is spotted. Such efforts merely "harvest" mice off of the larger populations, rather than providing control with any real impact on the larger problem.

Trapping and baiting programs are important, but proactive programs must also include rodent-proofing programs of not only doors, but also utility systems leading into buildings and each apartment. It is the responsibility of the pest professional to illustrate to the city building management those specific areas needing repairs and rodent proofing.

The building managers, on the other hand, must then address these issues. Expecting a pest professional to eliminate the mice from city environments without a total IPM approach is not realistic. In city neighborhoods containing established mouse populations, a non-IPM approach is the equivalent of the old expression of attempting to bail out the ocean with a teaspoon. Certainly for homes and apartments containing mouse allergen-sensitive individuals, harvesting programs will not suffice.

E-mail the author at rcorrigan@giemedia.com.
 

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A Rat in the Toilet Bowl: Act Professionally… And Don’t Panic!

City rats are capable swimmers and climbers, and thus it is not uncommon to hear of reports of the occasional "sewer rat" finding its way into a specific residential toilet. This happens in those systems where line breaks or sewer systems may be in disrepair. A rat that has emerged into a toilet bowl can be a frightening, even traumatic experience for a homeowner, especially those who may be rodent phobic. Consider the conflict of interest when an undressed (i.e., exposed and vulnerable) person attempts to sit down on a toilet containing a large rat attempting to come up and out. Many stories exist of this event over the years all around the world. While they may be humorous to retell, they are not at all funny to the person having had the experience.

Dealing with a toilet bowl rat is not difficult, although these rats have been subjected to some very bizarre attempts by grossed out, panicked homeowners attempting to kill the "attacking rat that was as big as an alley cat." This includes being shot at, electrocuted, stabbed (with a wide range of implements), bludgeoned, choked and other events too weird to believe. Of course, closing the lid and flushing the toilet is usually not helpful; although this is what a frightened homeowner does first. One homeowner admitted pouring D-Con into the toilet bowl with the rat, thinking the rat would succumb to the rat poison. Others report pouring a cup of bleach in the toilet, closing the lid, and removing a dead rat 10 minutes later (a technique that, in fact, will kill a rat).

A more professional approach. Pest professionals can remove toilet rats via the simple use of a wild animal loop snare, capturing the rat, and then placing it in a pillow case-type sack, and dealing with the rat outside of the account. Some use rat snap traps taped to short sticks and insert the trap into the toilet bowl. However, correctly positioning the trap is critical for successful capture. If the rat is captured by the foot, the nose, or some other non-lethal area, there can be substantial noise and pandemonium inside the bathroom. Glue board traps are not appropriate tools for this situation because there is too much moisture, preventing good adhesion.

As a novice PCO in New York City encountering a live toilet rat for the first time, I admit to first flushing the toilet and then eventually pinning down and crushing a toilet rat with the wand of a 1-gallon compressed air sprayer. It was neither pretty nor a "professional event," that’s for sure. I felt like I had been in a battle. I was just glad to get my ticket signed and leave victorious (and before any more could emerge).