A bed bug cover, also called a mattress encasement, is a zippered fabric casing that completely seals your mattress or box spring. It serves two purposes: trapping any bed bugs already living inside the mattress so they can’t feed and eventually die, and creating a smooth, sealed surface that prevents new bugs from burrowing into seams and hiding spots. If you’re dealing with bed bugs or trying to prevent them, an encasement is one of the most practical tools available.
How Bed Bug Covers Work
Bed bugs are flat, small insects that hide in the folds, seams, and crevices of mattresses and box springs during the day, then come out at night to feed. A standard mattress has dozens of hiding spots: piping, tufts, handles, vents, and the gap between the mattress and its label. An encasement eliminates all of these by wrapping the entire mattress in a sealed barrier.
When bugs are already present inside the mattress, the encasement locks them in. Without access to a blood meal, bed bugs held at room temperature die within about 70 days on average. Older studies from the 1930s and 1940s suggested bed bugs could survive over a year without feeding, but those were conducted in unheated European homes where temperatures dropped below 40°F. Modern research on bed bugs collected from temperature-controlled homes in the United States shows much shorter survival times. This means an encasement needs to stay sealed for several months at minimum to starve out any trapped population.
For prevention, the cover removes the mattress as a potential harborage site. Bed bugs on the outside of the encasement have nowhere to hide on its smooth surface, making them far easier to spot during inspections.
Features That Actually Matter
Not every mattress cover marketed for bed bugs will stop them. A basic allergen cover or waterproof protector is not the same thing as a bed bug encasement. Here’s what to look for:
- Full encasement design: The cover must wrap the entire mattress on all six sides. A fitted-sheet style protector that only covers the top and sides leaves the bottom exposed, which defeats the purpose.
- Bite-proof fabric: The material needs to be tightly woven enough that bed bugs cannot bite through it or squeeze through the weave. Look for products specifically labeled and tested for bed bugs, not just dust mites or allergens.
- Bug-proof zipper: The zipper is the weak point. Effective encasements use zippers with teeth small enough that even nymph-stage bed bugs (which can be smaller than 1 mm) cannot escape. A zipper end-stop or locking mechanism that secures the zipper tab in the closed position is essential, since bed bugs can work their way through even a tiny gap at the zipper’s end.
- Tear-resistant construction: A rip or worn spot turns the encasement into just another piece of fabric. Reinforced seams and durable material matter, especially around corners and the zipper area.
Cover Both the Mattress and Box Spring
If you only encase the mattress, you’re leaving the box spring unprotected. Box springs are actually a more common hiding spot than mattresses because they have a fabric underside with a hollow interior, exposed wooden slats, and plenty of crevices along stapled edges. Bed bugs can establish large colonies inside a box spring without being visible. Both the mattress and the box spring need their own encasement for the approach to work.
Installation Without Damage
The most common way a bed bug cover fails is a tear during installation or from the bed frame itself. Before putting the encasement on, inspect the bed frame and box spring for sharp edges, exposed bolts, staples, or rough spots that could puncture the fabric. Adhesive felt pads can be applied over these areas to protect the encasement from damage.
When sliding the encasement on, work slowly and avoid dragging it across sharp corners. It helps to have a second person hold the mattress at an angle. Once zipped shut, run your fingers along the zipper to make sure it’s fully closed and locked. Place your normal fitted sheet and bedding on top as usual.
Keeping the Cover Effective Long-Term
Once installed, the encasement should not be removed. Your regular sheets and bedding go on top and get laundered as normal, but the encasement stays in place continuously. Removing it, even briefly, can release trapped bugs or create an opportunity for new ones to get inside.
Check the encasement every few months for signs of wear. Look for small rips, holes, or thinning fabric, especially near the zipper and corners. If you find damage, the encasement needs to be replaced. Some people apply a small patch of fabric tape as a temporary fix, but a compromised encasement should be swapped out as soon as possible.
For active infestations where you’re using the cover to starve trapped bugs, plan to keep it on for at least a year to be safe, even though most bugs will die within a few months. There’s no downside to leaving it on permanently, and many people do.
What a Cover Won’t Do on Its Own
A bed bug encasement protects your mattress and box spring, but bed bugs don’t only live in beds. They hide in headboards, nightstands, baseboards, electrical outlets, carpet edges, and even behind picture frames. If you have an active infestation, encasing the mattress traps the bugs inside it and makes the bed easier to monitor, but it won’t address the bugs living elsewhere in the room.
Encasements work best as one part of a broader approach that includes thorough cleaning, reducing clutter around the bed, and in many cases professional treatment. What the cover does accomplish is significant: it saves your mattress from needing to be thrown out, removes the largest hiding spot in the room, and makes it much easier to spot any remaining bugs on the clean, light-colored surface of the encasement during routine checks.
For prevention, especially in apartments or when traveling frequently, encasements are highly effective as a standalone measure. They eliminate the mattress as a colonization site, which means any bugs that hitch a ride into your home have far fewer places to establish themselves before you notice them.