If you see a mouse in your kitchen, it might be a solitary scout. If you have an Eastern Gray Squirrel in your attic, it’s likely a mother raising a litter. But if you have Southern Flying Squirrels, you almost certainly have a crowd.

Flying squirrels are unique among our local rodents because of their highly social nature, especially in winter. While they are elusive and rarely seen by homeowners (being strictly nocturnal), they are one of the most common attic pests in wooded Louisville neighborhoods like Prospect, Crestwood, and the Highlands.

Understanding their social structure is critical to getting rid of them. If you catch one and think you’re done, you’ve left 95% of the problem behind.

The Winter Aggregation

Flying squirrels do not hibernate. They remain active all winter. However, they are small animals (about the size of a chipmunk) with a high surface-area-to-body-mass ratio. This means they lose body heat very quickly.

To survive the freezing Kentucky winters, they rely on social thermoregulation. They huddle together in large balls to share body heat. This behavior is called “aggregating.”

In the wild, they would pile into a hollow tree. In the suburbs, your attic insulation provides the perfect, limitless blanket.

The Numbers: A typical winter colony in an attic contains 10 to 20 individuals. However, we have removed colonies as large as 30 or 40 from a single home. These colonies are often composed of extended family groups, but unrelated squirrels will also join in for warmth.

The “Latrine” Effect

Because they live in such large groups, flying squirrels cause a specific type of damage that is different from other rodents.

Most rodents (like mice) poop and pee wherever they walk. Flying squirrels are cleaner; they designate specific areas of the attic as latrines.

• The Damage: Imagine 20 animals urinating in the same 2-square-foot spot every night for four months. The urine saturates the insulation, soaks into the drywall ceiling below, and causes brown stains to appear in your living room.
• The Smell: This concentrated waste creates a pungent, musky, ammonia-like odor that is distinct from the smell of mice or rats.

Why Standard Traps Fail

If a homeowner buys a standard squirrel trap (designed for a large gray squirrel) and puts it in the attic, two things happen:

1. Weight Issue: The flying squirrel is too light (2-3 oz) to trigger the heavy pan of a large trap. They steal the bait and leave.
2. Numbers Game: Even if you catch one, you have 19 left. Catching them one by one with single-set traps would take months. By the time you caught the last one, the first ones would have bred again.

The Professional Solution: Colony Traps

To effectively remove a flying squirrel colony, we use a different approach.

1. Exclusion First: We seal up every entry hole on the roof except for the main one.
2. Repeater Traps: We install a “repeater” or “colony” trap directly over the main exit hole. This trap allows multiple squirrels to enter but none to leave. As they exit the attic at dusk to feed, they push through a one-way door into the holding cage.
3. One-Way Doors: Alternatively, we use exclusion valves that let them fly out and glide away, but prevent them from landing and re-entering.

Because they are colony animals, once you evict the group and seal the hole, they generally stay together and move on to a natural den or a different structure. The key is ensuring you get the entire group out before sealing the final hole.