Bat Removal and Exclusion in Delaware

Start here if there has been contact

If a bat has been in a room with a sleeping person, an unattended child, or anyone unable to say reliably whether they were touched, that is a public health question before it is a pest control question. Contact the Delaware Division of Public Health first. Where possible the bat should be contained rather than released or destroyed, because testing may be relevant.

This is not a formality and it is not us being cautious for the sake of it. The rest of this page is about the structure. That part is about the people in it, and it comes first.

How bats get in

The gaps are far smaller than people expect. A bat does not need a hole it can fly through, only one it can crawl through, and the common house-roosting species in this region manage openings around three-eighths of an inch. That is a gap you would walk past.

The result is that bat entry points are almost never obvious damage. They are construction joints that have opened slightly with age and movement.

The usual openings

• Ridge vents, particularly where the sealing strip has lifted or degraded
• The gap where a chimney meets the roof, behind flashing
• Soffit and fascia joints, and the ends of aluminium trim runs
• Behind shutters, loose siding and trim boards on gable ends
• Gable vent louvres and any failed screening behind them
• Where a lower roof ties into a wall

What you notice first

Most people see the animals before they see any damage: bats emerging from one spot on the house at dusk, in ones and twos over twenty minutes or so. Watching the structure at dusk from a distance is genuinely the most useful diagnostic there is, and it is something a homeowner can do before anyone visits.

The other common signs are accumulating guano below an entry point — on siding, a windowsill, a deck rail or the ground in a line under the eave — a musty odour where a roost has been established for a while, and rub marks at the opening itself where oils from fur have darkened the surface.

Guano should not be swept or vacuumed. Disturbing accumulated droppings puts material into the air, and clean-up is handled with that in mind.

Exclusion, and why the calendar decides

Bats are not removed one at a time. The work is exclusion: every opening on the structure is sealed except the active ones, one-way devices go over those so animals can leave and cannot return, and once the roost is confirmed empty the last openings are closed permanently.

The part that is not negotiable is when. Bats are protected, and there is a period each year when young are present and cannot yet fly. Exclusion during that window seals flightless pups inside the structure, away from the adults, which is both inhumane and prohibited. Work has to sit either side of it.

We will tell you where the calendar sits when you call, and if it is a period when exclusion cannot be carried out we will say so rather than book it. Sealing a building with bats inside is the one outcome this work exists to prevent.

What bat work is not

There is no treatment for bats. Nothing is sprayed, nothing is baited, and no repellent, ultrasonic device or chemical has been shown to move a colony out of a structure. Anyone offering a treatment for bats is selling something that does not work.

Equally, one bat found flying in a living room is a different situation from a roost, and the two get handled differently. A single animal that came down a flue or through an open door does not necessarily mean a colony in the attic — though it is worth establishing which you have, because the answer changes what needs doing.