Safely removing bats from your attic can be a long process. Which is why before starting it is important to understand the following:
- It is illegal to poison bats in most states. The only humane, legal, and effective method for removing bats is live bat exclusion, which is described in this article.
- Bats are protected because they are 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 bat before starting the exclusion process. The most common bats found in most attics are the Mexican free-tailed bat, the little brown bat, and the Virginia big-eared bat. Knowing the species is essential so you know the bat’s maternity season.
- Female bats roost in attics because they resemble a cave—warm, dark, and protected. Female bats give birth to and raise one bat pup each season. The maternity season runs from late April to early August, depending on the bat species. It is illegal to remove bats during this time because it will kill the bat pups. Therefore, exclusion is limited to early spring before pups are born or later August/early September once bat pups can fly.
Signs of bats in your attic
Although 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 leaving or entering your home near the roofline, usually around the time the sun sets. You may also see brown or grayish stains near entry/exit points.
- Smell. Bat guano and urine has a pungent odor that grows stronger over time. Guano can ruin wood and drywall and promotes mold growth. Dried guano can also put toxic fungal spores into the air.
- Sound. Although bats are fairly quiet, you may hear scraping, rustling, and squeaking.
Removing bats from your attic
So here are how to remove bats from your attic safely and legaly.
Step 1: Identify the species to determine when exclusion can begin
If possible, identify which bat is living in your attic so you can determine the 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, conduct a “night watch” for several nights. This involves going outside 15 minutes before dark to see where bats exit. Bats may leave in groups, and there may be more than one exit/entry point. Exit/entry points may be marked by dark grayish stains (from bat body oils) or brown streaks (guano). Carefully note where bats are leaving as this is where exclusion traps will be placed.
Step 3: Seal up cracks and holes
Before placing exclusion traps, seal all holes and cracks greater than 3/8 inches with silicone caulk. Larger holes can be sealed with boards or screening material. Do not seal the entry/exit points—only other holes or cracks you find. This is to prevent bats from finding another entry/exit point after placing the bat exclusion traps. You’ll need to use a ladder for this process as you’ll need to carefully inspect everywhere around your roof, including vents.
Step 4: Place bat exclusion traps
Once all cracks and holes are sealed, place bat exclusion traps (called bat cones) at entry/exit points. You can purchase bat cones online. 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. Bat cones allow bats to leave your attic, but they cannot get back in due to the angle and slippery material. Think of them as one-way bat doors. Leave the bat cones in place for a few days to ensure that all bats are out of the attic. Conduct additional night watches to assess activity.
Step 5: Seal up entry and exit points
Once you’re satisfied that all bats have left your attic, remove the bat cones and seal up the exit/entry holes using wood, screens, or caulk, depending on the size and type of hole. It is critical to do a good job so they don’t return to your attic. Bats live for a long time and will return to roosting sites, so you don’t give them an opening.
Step 6: Clean up
The final step is to clean up the bat guano in the attic. Wear protective gear and a respirator to avoid inhaling dried spores. You can shovel the guano into trash bags and seal for disposal. You may need to vacuum up the remainder. Replace stained insulation and any damaged wood or drywall. Finally, use an enzyme cleaner (such as D-Molish Now, an organic stain cleaner and odor remover) to remove the odor. It is critical to remove the smell so it doesn’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 may give bats with 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.