There are a few solid options that can help close gaps and discourage insects from sneaking in:

• Door sweeps: Screw-on or clip-in sweeps with vinyl or brush seals create a durable barrier along the bottom edge.
• Self-adhesive silicone bottom seals: Flexible strips that stick to the door and contour to floors.
• Under-door draft stoppers: Double-sided foam sleeves slide under the door to block light, air, and dust.
• Magnetic screen doors: Great when you want fresh air with the door open while keeping bugs out.
• Weather stripping for sides/top: Completes the perimeter seal so insects have fewer pathways.

Measure your gap and door width before buying, and pick materials suited to your floor (smooth vs. carpet). Results can vary based on the door, threshold, and installation.

Sealing gaps is a practical, non-chemical way to discourage pests from slipping inside:

1. Measure the gap at the bottom of your door to choose the right solution.
2. Install a door sweep (rigid or brush style) or a self-adhesive silicone seal so it lightly contacts the floor without dragging.
3. Fill side and top gaps with weather stripping to tighten the full perimeter.
4. Use an under-door draft blocker on smooth floors for extra coverage inside.
5. Check the threshold for uneven spots and add a low-profile threshold plate if needed.
6. Keep the area clean by sweeping up crumbs and moisture that can attract pests.

These steps can reduce entry points, though effectiveness depends on your door, floor surface, and maintenance.

If you want a quick DIY, a self-adhesive silicone strip is a simple option:

1. Clean and dry the door bottom thoroughly so the adhesive sticks well.
2. Measure and cut the strip to your door width.
3. Position the strip so the fin just brushes the floor—enough to close light gaps without rubbing hard.
4. Peel and press the adhesive in place from one side to the other, keeping it straight.
5. Let it set per the instructions, then open and close the door to check clearance.

For larger or uneven gaps, an adjustable screw-on door sweep offers more rigidity. Pairing with weather stripping on the sides and top can improve results. Performance varies with gap size and floor type.

Under-door draft blockers can help by filling small to moderate gaps where light and air pass through—conditions that often make it easier for bugs to slip in.

• When they work well: Smooth floors, a consistent gap, and a snug, cut-to-length fit.
• Where they struggle: Deep carpet, uneven thresholds, or heavy foot traffic that shifts the blocker.
• Fit matters: Choose the right length and thickness, center it under the door, and trim if the design allows.
• Pairing helps: Combine with a door sweep and side/top weather stripping for a more complete seal.
• Care: Occasionally clean and reposition to maintain contact with the floor.

They can improve comfort and reduce pathways for insects, but effectiveness varies by gap size and surface.

Getting the right size ensures the magnets meet cleanly for a better seal:

1. Measure your doorway—width and height of the opening you’ll cover (inside the frame or on the trim).
2. Match the listing: Choose a screen that lists a “fits door size” range equal to your measurements.
3. Allow a little overlap if mounting to trim so the hook-and-loop or tacks grip securely.
4. Check the center alignment so the magnetic closure lines up and closes hands-free.
5. Consider traffic: For pets and frequent use, look for dense mesh and continuous magnets.

You can filter by size on Walmart’s site to narrow options. Fit and performance depend on your frame, surface, and installation.