Little brown bat, Myotis lucifugus

Bats

Bats, the only mammals capable of true flight, eat vast quantities of insects. Only a few of the 40 species of bats found in the United States and Canada cause problems, primarily when they form roosts or maternity colonies in human dwellings or structures. Those most commonly encountered in pest situations are the little brown bat, big brown bat, Mexican free-tailed bat, pallid bat in the South-west, and Yuma myotis in the West (Greenhall 1982, Frantz 1986). Species identification may be difficult but is important because several bat species are endangered and protected by state and federal law. Control operators unfamiliar with bat identification are urged to seek professional help from wildlife agencies or universities (Frantz 1986).

The presence of bats in a building is usually evidenced by noise (squeaking, scratching) and by the presence and distinctive pungent odor of the accumulated fecal droppings and urine. Bat feces are readily distinguished from those of rodents by odor, insect con-tent, and the ease with which they are crushed (Greenhall 1982).

Many people are fearful of bats and panic in their presence. Bats occasion-ally contract rabies, and although few human deaths have resulted from bat-transmitted rabies (Greenhall 1982), contact with a rabid bat or a bite by a bat that escapes requires post exposure treatment of people and pets without current vaccinations (Frantz 1986). The fungal causative organism of histoplasmosis, a respiratory disease of humans, can develop where bat colonies are allowed to persist and guano deposits accumulate. Bats roosting near airports may be hazardous to air-craft (Kincaid 1975).

Summary of Damage Prevention and Control Methods

Exclusion

Polypropylene netting check valves simplify getting bats out.

Quality bat-proofing permanently excludes bats.

Initiate control before young are born or after they are able to fly.

Repellents

Naphthalene: limited efficacy. Illumination.

Air drafts/ventilation.

Ultrasonic devices: not effective. Sticky deterrents: limited efficacy.

Toxicants

None are registered.

Trapping

Available, but unnecessarily complicated compared to exclusion and bat-proofing.

Other Methods

Sanitation and cleanup.

Artificial roosts.

Removal of Occasional Bat Intruders

When no bite or contact has occurred, help the bat escape (otherwise submit it for rabies testing).

Conservation and Public Education

Information itself functions as a management technique.