Safely removing bats from your attic can be a long process. This is why, before starting, it’s important to understand the following:
- It’s illegal to poison bats in most states. The only humane, legal, and effective method of removing bats is live bat exclusion, which we’ll describe in this article.
- Bats are protected because they’re good for the ecosystem. One bat can eat almost 1,000 mosquitoes in one night, eliminating the need for you to use different insect-repelling methods. They also help pollinate plants and disperse seeds.
- Identify the bats before starting the exclusion process. The most common bats found in attics are the Mexican free-tailed bat, the little brown bat, and the Virginia big-eared bat. Knowing the species is essential to knowing the bat’s maternity season.
- Female bats roost in attics because they resemble caves: dark, warm, and safe. Female bats give birth to and raise one bat pup each season. Their maternity season runs from late April to early August, depending on the bat species. It’s illegal to remove bats during this time because it will kill the bat pups. For this reason, the exclusion is limited to early spring (before the pups are born) or late August/early September (once the pups can fly).
Signs of Bats in Your Attic
Even though bats aren’t destructive, bat guano can be a significant problem. Over time, bat roosts can accumulate significant amounts of bat droppings.
Signs of bats in your attic include:
- Visual evidence: You can see bats exiting or entering your home near the roofline, usually around sunset. You may also see brown or grayish stains near entry/exit points.
- Smell: Bat guano and urine have a pungent odor that grows stronger over time. Guano can ruin wood and drywall and promotes mold growth. Dried guano can also release toxic fungal spores into the air.
- Sound: Although bats are fairly quiet, you may hear scraping, rustling, and/or squeaking.
Removing Bats From Your Attic
So, here’s how you can remove bats from your attic safely and legally.
Step 1. Identify the species to determine when exclusion can begin.
If possible, identify the kind of bat living in your attic so you can determine its maternity season. If you’re unable to do this, play it safe and don’t start the process until early September.
Step 2. Locate entry and exit points.
To determine where bats are entering and exiting your attic, hold a “night watch” for several nights. This involves going outside 15 minutes before dark to see the bats’ exit point. Bats may leave in groups and there may be more than one exit/entry point. Exit/entry points can be marked by dark grayish stains (from bat body oils) or brown streaks (guano). Carefully note where the bats are leaving from as this is where you’ll place your exclusion traps.
Step 3. Seal any cracks or holes.
Before placing exclusion traps, seal all holes and cracks larger than 3/8 in. (0.95 cm) with silicone caulk. You’ll need to use a ladder for this process as you’ll need to carefully inspect everywhere around your roof, including vents. You can seal larger holes with boards or screen material.
Don’t seal the entry/exit points, only any other holes or cracks you find. You want to stop bats from finding another entry/exit point after placing the bat exclusion traps.
Step 4. Set bat exclusion traps.
Once you’ve sealed all cracks and holes, place bat exclusion traps (also called bat cones) at entry/exit points. You can purchase these online.
Bat cones allow bats to leave your attic, but they can’t get back in due to the angle and slippery material. Think of them as one-way bat doors. Experts recommend purchasing bat cones rather than constructing your own. Depending on where the entry/exit spots are, you may need to buy specialized bat cones designed for angled areas.
When installing the bat cones, carefully secure the base end over the exit/entry spot and ensure there are no holes or gaps. Fasten it securely with screws or staples. Leave the bat cones in place for a few days to ensure that all bats are out of the attic. Continue to hold your night watches to check the amount of bat activity.
Step 5. Seal any entry or exit points.
Once you’re satisfied that all bats have left your attic, remove the bat cones. Seal the exit/entry holes using wood, screening, or caulk, depending on the size and type of hole.
It’s critical to do a good job to ensure the bats won’t return to your attic. Bats live for a long time and will return to roosting sites, so you don’t leave them any opening.
Step 6. Clean up.
The final step is to clean up the bat guano. Wear protective gear and a respirator to avoid inhaling dried spores. You can shovel the guano into trash bags and seal them for disposal. You may need to vacuum up any remainders.
Replace stained insulation and any damaged wood or drywall. Finally, use an enzymatic cleaner (such as D-Molish Now, an organic stain cleaner and odor remover) to remove the odor. You need to remove the smell so it won’t attract more bats.
After the bats are gone, you may want to place bat houses as close to the old entry/exit points as possible. Although you don’t want them in your home, bats are good to have nearby, especially for mosquito control. Although there’s no guarantee that they’ll use them, bat houses offer bats a new roosting place.
Place bat houses as high as possible – at least 15 feet off the ground – and as close to the previous entry/exit points as possible.