Bat netting is lightweight mesh used to either exclude bats from buildings or protect fruit trees from feeding damage. The most common type is 1/4-inch black polypropylene netting installed over entry points on homes and structures, allowing bats to leave but not return. Getting the mesh size, material, and timing right matters both for effectiveness and for avoiding harm to bats, which are legally protected in most states.
How Bat Exclusion Netting Works
Exclusion netting is draped over the gaps, cracks, and openings where bats enter a building. It’s attached along the top and sides but left open at the bottom, creating a one-way exit. Bats can crawl down and out through the loose bottom edge, but the netting blocks them from flying or crawling back in. Once all bats have departed (usually within a few days to a week), the entry points are permanently sealed.
This approach is considered the standard humane method for removing bat colonies from attics, soffits, and wall voids. Trapping, poisoning, and fumigation are illegal for most bat species. Exclusion netting, along with one-way tubes and cones, gives bats a path out without injuring them.
Mesh Size and Material Specs
Standard bat exclusion netting uses 1/4-inch mesh, which is small enough to block re-entry for all North American bat species. It’s typically sold in panels (a common size is 14 by 10 feet) made from biaxially oriented polypropylene, a plastic that’s been stretched during manufacturing to make it stronger and lighter than regular extruded mesh. The strand count runs about 4 per inch in both directions.
The material is stiffer than regular window screen but still flexible enough to drape and move when bats push against it from behind. Black is the standard color because it blends with rooflines and shadows, making installations less visible. Polypropylene holds up well in sun and rain, though prolonged UV exposure will eventually degrade it over a year or two, which is fine since exclusion netting is temporary.
One important requirement from wildlife management guidelines: any netting or one-way device used for bat exclusion must be free of sharp edges and must not create gaps where bats can get tangled. Loose threads, frayed cuts, or poorly secured edges can trap bats by their wings, causing injury or death.
When You Can and Can’t Install It
Bat exclusion is restricted by season in most states because of maternity colonies. Female bats gather in warm, sheltered spaces (like your attic) each spring to give birth and raise pups. Newborns can’t fly for several weeks. If you install exclusion netting while flightless pups are inside, the mothers leave and can’t return, and the pups die trapped in the structure.
In Florida, exclusion is illegal from April 16 through August 14. Other states have similar windows, though exact dates vary by region and species. Northern states with shorter summers may have a narrower restricted period, while southern states with longer warm seasons tend to have broader ones. The general rule across the U.S. is to avoid exclusion from roughly mid-May through mid-August, but check your state wildlife agency for specific dates.
The best time to install exclusion netting is early fall, after pups are flying but before bats settle into winter hibernation sites. Late September through October works well in most climates. Spring exclusion is also possible if you finish before maternity season begins, but timing is tight.
Installing Exclusion Netting on a Building
Before putting up any netting, you need to identify every entry point on the building. Bats can squeeze through gaps as small as 3/8 of an inch, so this means inspecting the entire roofline, soffit joints, gable vents, chimney flashing, and any place where different building materials meet. Watch the building at dusk to see where bats emerge.
The netting gets stapled or taped along the top and both sides of each opening, with the bottom edge hanging free about 12 to 18 inches below the entry point. That loose bottom flap is critical. If you secure it too tightly, bats can’t exit. If you leave too much slack, bats may find their way back in along the edges. The netting should hang close to the wall but not be pressed flat against it.
After several days of warm, dry weather (bats don’t fly in rain), you can assume the colony has departed. Remove the netting and permanently seal every opening with caulk, steel wool, flashing, or hardware cloth. Leaving even one gap unsealed means bats will recolonize the space, sometimes within days.
Professional wildlife control operators typically handle both the exclusion and the sealing as a single job. If you’re doing it yourself, the netting is inexpensive, but the sealing work on a multi-story home can be extensive and may require ladder or scaffold access.
Fruit Tree and Garden Netting
In regions with fruit bats or flying foxes, netting serves a different purpose: protecting orchards and backyard fruit trees from feeding damage. The key concern here is preventing bat entanglement, which kills thousands of flying foxes each year in countries like Australia.
The Queensland Government recommends knitted mesh with an aperture smaller than 5mm by 5mm (about 3/16 of an inch) when the mesh is stretched, woven from strands at least 500 microns thick. This is much finer than typical bird netting, which often has openings large enough for bats to push their heads or wings through and become hopelessly tangled. Loose, thin monofilament netting is the worst offender.
The netting should be installed over a rigid frame rather than draped loosely over branches. Loose netting sags and creates pockets where bats, birds, and possums get caught. A properly tensioned net over a frame structure keeps wildlife from pressing against it with enough force to get entangled. Secure the edges all the way to the ground or trunk so animals can’t enter from below.
Disposal and Decontamination
Bat exclusion netting that has been in contact with bats or their droppings should be disposed of or decontaminated after use. Bats can carry the fungus that causes white-nose syndrome, a disease devastating bat populations across North America. Wildlife management guidelines recommend treating any mesh, cones, or tubes used in exclusion work as potentially contaminated. If you’re reusing equipment between jobs or sites, cleaning it helps prevent spreading the fungus to new bat colonies.
For homeowners doing a one-time exclusion, simply bagging and discarding the netting after the job is the easiest approach. Bat guano (droppings) left in the attic is a separate concern, as it can harbor a fungus that causes a respiratory infection in humans. Cleanup of large accumulations is best left to professionals with proper respiratory protection.