Cleaning, disinfecting needed to bat-proof home

Bat use roosting niches that are indoors (such as inhabited buildings, out buildings, barns, warehouses), semi-enclosed spaces (such as loading docks, entrances and foyers), partially sheltered spaces (such as porches, carports, pavilions, highway underpasses, bridges) and open structures. Once there, active bat infestations can have severe economic and aesthetic effects, often intertwined with public health issues.

Surface areas often have rub marks on the walls, under loose woodwork, between bricks and around other entryways. These entryways look smooth and polished in appearance. The stained area is slightly sticky, may contain a few bat hairs, and be yellow-brown to blackish-brown in color. The smooth gloss of these rub marks is due to the oils from fur and other body secretions mixed with dust, deposited there by many animals that have passed through there repeatedly.

Disturbing sounds may be heard from vocalization and grooming, scratching, crawling or climbing in attics, under eaves, behind walls and between floors. Bats become noisy on hot days in attics.

Fecal pellets indicate the presence of animals and are found on attic floors, in wall recesses and outside the house at its base. Fecal pellets along and inside walls may indicate the presence of mice, rats and even roaches. Since most house bats north of Mexico are insectivorous, their droppings are easily distinguished from those of rodents. Bat droppings tend to be segmented, elongated and friable. When crushed, they become powdery and reveal shiny bits of undigested insect remains. In contrast, mice and rat droppings tend to taper, are unsegmented, are harder and more fibrous and do not become powdery when crushed unless extremely old.

Bat excrement produces an unpleasant odor as it decomposes in attics, wall spaces and other voids. The pungent, musty, acrid odor can often be detected from outside a building containing a large or long-term colony. Similar odor problems occur when animals die in inaccessible locations.

The odor also attracts arthropods, which may later invade other areas of the building. Bat feces also provide a medium for other microorganisms, some of which are pathogenic — histoplasmosis, for example. The guano accumulation can fill space between walls, floors and ceilings. It can cause a slippery hazard on floors, steps and ladders. The weight of it can cause ceilings and floors to collapse. Accumulation also results in stained ceilings, soffits and siding.

Bats are not asymptomatic carriers of rabies. After an incubation period of two to six weeks, they become ill with the disease for as long as 10 days. During the latter period, a rabid bat's behavior is generally not normal — it may be found active during daytime or on the ground, unable to fly. Most human exposures are the result of accidental or careless handling of grounded animals. Sometimes bats that are ill may be involved in unprovoked attacks on people or pets. It is during this stage that rabid bats are capable of transmitting the disease by biting another mammal. The virus in the carcass can remain infectious until decomposition takes place.

Histoplasmosis is a very common lung disease caused by a microscopic fungus — Histoplasmosis capsulatum. Histoplasma exists in nature as a saprophytic mold that grows in soil with high nitrogen content, generally associated with the guano and bird debris. The disease can be acquired by the casual inhalation of wind-blown spores, but infections are more likely to result from visits to point source of growth of the fungus. Relative to bats, such sources include bat roosts in caves, barns, attics, and soil enriched with bat feces.

There is currently no EPA-approved pesticide in use to control bats. The only long-term control method is to bat-proof the home or building in which the colony is roosting. This has to be done at night when the colony is gone since trapped bats will soon die, causing a foul odor.

Main access points to the structure are found in observing the animal leaving the building at dusk. Once the space is empty, the area should be flooded with light for several weeks. All cracks and crevasses must be caulked or stuffed with heavy hardware screen.

Once the dwelling has been vacated, any caked fecal material or crystallized urine should be removed from flooring and beams. The odor of bat excrement acts as a pheromone which will attract other bats. Respirators and protective clothing must be worn while working in the roost.

All contaminated insulation must be discarded. Surfaces contaminated with urine and feces must be disinfected by spraying with a solution of bleach and water. Masking agents should be applied after the area has been disinfected to kill any remaining odor. If the ceiling drywall is stained, it should be removed and replaced with new drywall. Once the attic has been cleaned and disinfected, new R-38 insulation should be reinstalled.

Bats are beneficial to our environment because of the large quantities of insects they eat. Without them, humanity would have larger problems.

If you would like to share a cleaning idea or concept with the reading audience, call Ed at NWES (255-2266) or send them to Bonner County Daily Bee, 310 Church St., Sandpoint, Idaho, 83864; Attn: What Would Ed Do?

Copy written by Edmond E. Madan, certified forensic, fire, flood, mold inspection and remediation contractor. Ed is the CEO of Northwest Executive & Environmental Services, LLC.