Bats in structures


August 3, 2022


Kevin Cornwell, CWCP, owner of Cornwell’s Wildlife Control, Carrollton, Va., left, and Jim Goins, owner of Virginia Wildlife Management, Gloucester Point, Va., discuss bat-proofing roofs at a recent NWCOA training seminar. PHOTO: CHARLES HOLT

Treating for bats in a residential or commercial structure can provide a recurring revenue stream, but it also can pose some unusual challenges.

Bats in structures are often a symptom of other issues, such as construction gaps, products provided to the building trade that are not bat-proof, poor workmanship, etc. Unlike rodents, bats are not gnawing structures to gain entry; however, some chewing through spray foam sealant has been documented at bat accounts.


Bat calls from customers basically come in three “flavors”:

1. A random bat that entered through an open window or door will require hand removal. This type of call has to be vetted through inspection, though, as bats living in an attic or other void areas of structures can find their way into the structure’s interior. There are specific protocols from the Centers for Disease Control and Prevention (CDC) concerning bats in the interior of homes that must be followed. These protocols can be found online at

The basic control method is to have clients try to confine the bat to a room if possible, before you arrive and remove it. You’ll need shoe covers, bite gloves (I prefer Kevlar-lined), biohazard bags and other holding containers, and a sign-off sheet detailing CDC bat protocols that clients must sign for both their and your protection. You also should have an infrared camera to locate the bat, and a stepladder in case you locate it out of arm’s reach.

2. Non-maternal bats are actively overwintering in a structure during the winter months when food isn’t available. While you also can have a grouping of non-maternal bats in a structure or feeding site, bats in vents during transition, or loafing bats under porch overhangs, etc., for the scope of this article, let’s focus on overwintering bats.


Guano cleanup comes with the territory. Wear the proper personal protective equipment (PPE) for this service. PHOTO: CHARLES HOLT

Depending on sun exposure, the temperature within the structure, and other factors, the bats themselves decided during warmer weather this could or could not also be a maternity site. Bats overwintering in structures result in many “bat-in-interior” calls during the winter months.

A cold snap or warm-up will have the bats searching for that perfect temperature zone. This results in bats entering structures; unlike a random bat, this occurs during times of the year when bats are not actively flying or leaving structures. Address this type of issue through exclusion methods, including the proper use of bat escape valves, when temperatures reach appropriate and approved levels.

3. Maternal bat colonies are comprised of female bats and their pups. This scenario often is the most dramatic in the form of guano accumulation, as the bats are actively feeding every night — barring inclement weather — and often become generational, with females and their offspring returning to the same structures to give birth. Address this type of issue with exclusion and the use of bat escape valves after all black-out regulations/periods are over.


Bat exclusion is the physical work done to a structure to make it bat-proof. Bats have strong site fidelity, so performing a detailed inspection of the structure is key. All areas being used by bats, and those offering entry potential, must be addressed for an exclusion program to succeed.

First, learn when the bat black-out periods are in your local markets. These are time periods when flightless bat pups are in structures. While secondary entry points can be sealed based on state regulations, the primary entry points cannot have escape valves installed yet because the adult bats would exit and strand the flightless pups inside. And while this is a bat protection issue — remember, bats aren’t rodents; they only have a pup or two per year — it’s also a “protect your clients” issue: The odor and/or sight of flightless, crawling bats throughout the interior of your client’s home is an issue you will avoid at all costs.

If you are able to perform the exclusion, be aware that if done improperly, it can result in some horrific issues. For example, bats trapped in homes often make it into the interior of homes. Because rabies is endemic in bat populations, CDC protocols come into effect. If you haven’t priced post-exposure rabies vaccination lately, you will be shocked.

Add to that the emotional distress and other factors your client’s attorney will come up with, along with the negative publicity online and in your community. You’ll want to avoid bat re-entry at all costs.

That includes making sure all the bats leave the premises. Bats aren’t very large, but their numbers within a structure can be so that, with dead bats and the biomass of a grouping of bats within a structure, odor issues can be extreme. This results in extra costs to you, plus brings back into play that dent in your reputation issue.

As bats are fairly long-lived, many operators have successfully ended bat colonization of a structure for years — only to have a new roof, storm damage or other work performed on structures that let the bat population rebound. This tells us those bats were actively exploring the structure every year until something changed, allowing their entry once again. Thus, make sure that any exclusion products you use will stand up to whatever warranty you provide. Also, reinspection visits and ongoing warranty renewals are commonly applied to bat exclusion accounts.


The National Wildlife Control Operators Association (NWCOA) offers two bat training courses that address all issues within this article and more.

⦁ Bat Standards is an online course that functions as a starting point to understanding bat biology,
entry points, zoonotic issues and more. It will be offered next on Sept. 7. Learn more and register at
⦁ The Bat Standards course mentioned above is the prerequisite to the Structural Bat Management course, which takes place in person over two days and includes structural mockups to perform metal bending (break work), metal scribing and other exclusion techniques. This course also offers a safety overview and attic remediation tips, and requires the inspection of a structure and a written estimate presented to instructors. It will be offered next in Mount Pleasant, N.Y., Sept. 16-17. Learn more and register at

If you perform bat work, or are thinking of adding this challenging, but highly profitable revenue stream, I highly recommend taking both courses. I hope to see you there.


A non-maternal colony literally hangs out together for the winter. PHOTO: CHARLES HOLT

Expand your bat-cabulary

⦁ Escape valve: A device installed over primary entry and exit points that allows bats to exit structures. It is a one-way system, so bats exit but cannot re-enter.

⦁ Guano: Bat droppings often are misidentified as rodent droppings. Becoming a “poopologist” is very helpful in wildlife control. As we like to say, “you really need to know your…”

About the Author

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Charles Holt, CWCP, CNI, MN, is a board members of the National Wildlife Control Operators Association. Learn more at

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