The 40-Bat Carmel Colony - DNR-Compliant Exclusion in One Season
A late-June bat in the living room. Five quotes. Three companies willing to break Indiana DNR law to take the job. One season later, the colony was gone and the house was sealed. Here is how the work actually went.
One bat in the living room is rarely one bat
The homeowner called on a Tuesday in late June. A bat had been swooping through the upstairs hallway around 9:30 PM the night before. Her husband had caught it under a laundry basket and released it outside. They had two kids under ten. The pediatrician had already told them they probably needed rabies post-exposure shots because nobody could swear the kids had not been bitten in their sleep. They wanted the house sealed by the weekend.
She had called five companies. Three of them said they could come out on Thursday or Friday and "bat-proof" the house immediately. One of those three was willing to start the exclusion in July. In Indiana, that would have been illegal. Indiana DNR rules treat the maternity period from roughly May 1 through August 1 as a blackout window. During those months, female bats are raising flightless pups inside the colony. Sealing the colony out during maternity traps the pups inside the structure where they die in the walls, and the law treats that as the take of a non-game protected species.
The fourth company told her they did not work on bats. The fifth was us.
What we found on the first walk
We arrived the next afternoon. The house was a 2008-build two-story in a Carmel neighborhood north of 116th, brick on three sides with cedar-shake gable returns and a steep cut-up roof line with four dormers. Cut-up roof lines are bat heaven. Every dormer corner, every gable peak, every soffit-to-wall transition is a potential entry.
Inside the attic we found droppings concentrated along two roof rafters near the front gable, dark staining on the underside of the OSB deck near a dormer return, and the unmistakable smell of an active maternity colony. We did not see live bats during the daytime walk - they were tucked into the soffit cavities and behind the gable trim where we could not safely reach without tearing finished work apart. We told the homeowner not to do that.
That evening, the team came back for a dusk emergence count. We set up at 8:40 PM and watched the house from two angles. Between 9:05 and 9:45, we counted 38 confirmed exits from the front gable peak, plus a handful of partial counts from a ridge gap on the back of the house that put the colony at somewhere between 38 and 42 bats. That is a real maternity colony, not a stray.
The species was almost certainly big brown bat (Eptesicus fuscus) based on size, exit timing, and the structural preference. We never handle bats in a way that requires positive species ID without DNR coordination, but every protected species in Indiana is protected during maternity, so the answer would have been the same either way: wait.
Why we told them to wait six weeks
The homeowner did not love this answer. We sat at her kitchen table and walked through the calendar. The pups inside the colony were flightless. Most of them would be flying with their mothers by late July. By August 1, the DNR considers the maternity season closed and exclusion work legal again. We scheduled the exclusion start for August 5, gave them a written protocol for the six-week wait, and helped them think about the rabies question with their pediatrician.
The protocol for the wait was practical. Close the attic access. Seal the interior of any obvious wall penetrations on the upper floor - around can lights, bath fans, attic hatches - with painters tape and weatherstripping. Do not attempt to seal the exterior entries. Do not run the attic fan in a way that draws air down into living space. Sleep with bedroom doors closed.
We did one welfare check at the three-week mark to confirm the colony was still using the same exits. They were.
The August exclusion, step by step
On August 5 the team arrived at 7:00 AM with a 32-foot ladder, a 24-foot articulating ladder, three one-way exclusion devices, a roll of half-inch hardware cloth, polyurethane sealant in matched colors, HEPA-vacuum gear, and full PPE.
We installed one-way exclusion devices on the three primary entries: the front gable peak vent, the rear ridge gap above the master bedroom, and a dormer corner on the east elevation where the cedar-shake return had pulled away from the fascia. One-way devices let bats exit at dusk but not re-enter. We left those devices in place for 10 days to let every last animal find its way out.
While the one-ways were running, we worked the secondary gaps. There were 14 of them across the house. Most were soffit-to-wall transitions, gable trim board ends, and small gaps where the cedar shake met flashing at the dormer cheeks. We sealed each one with hardware cloth backing and then polyurethane sealant tooled to match the existing trim color. None of this work was visible from the ground.
On day 11 we returned, confirmed zero bat activity at dusk for two consecutive evenings, removed the one-way devices, and permanently sealed the three primary entries with hardware cloth and matched sealant.
Then we went into the attic for cleanup. Guano had accumulated in two zones along the front rafters, roughly 30 square feet of contaminated decking total. We removed it in full PPE with a HEPA-filtered vacuum, double-bagged the waste for legal disposal, and decontaminated the affected attic section with an enzymatic cleaner rated for bat guano and histoplasmosis risk reduction. The contaminated insulation in that 30-square-foot zone came out. We replaced it with R-49 blown cellulose to match the rest of the attic.
What it cost
Total project: $2,800. That broke down roughly as $400 for the inspection and dusk count (credited to the project), $1,650 for the exclusion work itself across two days of labor and materials, and $750 for the guano cleanup, insulation replacement, and decontamination of the affected attic section. The homeowner's policy did not cover any of it because they had only seen the one interior bat and could not document structural damage to the insurer's satisfaction. With a documented contamination zone of 200+ square feet, an insurance claim is usually viable. At 30 square feet, it was not worth the deductible.
We backed the work with our two-year exclusion warranty.
The version where they hired the July guy
If the homeowner had hired the company that was willing to start in July, three things would have happened. First, the work would have been illegal. The DNR can issue citations and the homeowner can be on the hook if the contractor was unlicensed. Second, the flightless pups would have been trapped inside the wall cavities and soffit boxes. They would have died there over the following 10 to 14 days. The homeowner would have smelled it. We have been called to several houses to remove the resulting carcasses from inside finished walls, which is a much more expensive job than the original exclusion. Third, the surviving adult females, blocked from their pups, often punch new entries within 48 hours. The exclusion fails and the colony relocates two feet to the left.
We have seen all three outcomes on other people's work. The crew has spent more weekends than we want to count cutting open drywall to retrieve dead pups from inside a wall someone else sealed in July.
Timing matters more than speed
The homeowner who waits six weeks and pays $2,800 for a done-right exclusion is in a better position than the homeowner who pays $1,900 in July and then $3,000 again in October to fix the failure. Bats are not a panic species. They are a calendar species. The right answer in June is almost always "we will be back in August," and the right company will tell you that even when you are upset about it.
Eighteen months later, the front gable is still tight. No droppings on the deck. No swooping in the hallway. No second call.
Think you have bats?
If you have seen one in the house, heard scratching in a gable wall at dusk, or found droppings on a porch directly under a soffit corner, the team can do a dusk emergence count and tell you what you actually have.
Schedule an Inspection → (317) 512-3779