Few things are more frustrating than trying to relax at home while flies buzz around your kitchen or living room. You swat, you shoo, you even try closing every door—but somehow, they keep showing up. If you’ve noticed an increase in flies getting in the house lately, the culprit might not be your doors at all. Old or damaged windows can be an open invitation for pests, and understanding why can help you fix the problem for good.

Tiny Gaps, Big Problems

Even the smallest gaps in your window frames or seals can let insects sneak inside. Flies don’t need much space to enter—just a millimeter-wide crack can be enough. Over time, wooden frames can warp, caulking can crack, and weatherstripping can wear down, creating multiple entry points you might not even see. If your windows feel drafty or let in moisture, they’re probably letting in pests, too.

Damaged or Missing Screens

One of the most common reasons for flies getting in house is damaged screens. A small tear or hole in a window screen is like a welcome sign to flies, mosquitoes, and other bugs. Sometimes the damage isn’t obvious until you inspect closely—look for frayed edges, loose corners, or tiny punctures. Screens can also lose their tension over time, leaving gaps along the sides where pests can slip through.

Poorly Fitted Windows

If your windows no longer fit snugly in their frames, you could be dealing with bigger gaps than you realize. This can happen if the frame has shifted, the window has warped, or the installation wasn’t done correctly in the first place. In some cases, seasonal temperature changes can expand or contract materials, making the problem worse during certain months.

Attracted by Light and Warmth

Flies are naturally drawn to light and heat. If your windows leak warm air in the winter or cool air in the summer, they can create microclimates that attract insects to linger around your home. Once they find a weak spot—whether it’s a loose seal or a hole in the screen—they’ll take advantage of it.

Old Windows Mean More Maintenance

Older windows often require more upkeep to stay pest-proof. Wooden sashes can rot or swell, aluminum frames can corrode, and vinyl can warp over time. As these materials deteriorate, they create gaps that are perfect for bugs to slip through. Replacing weatherstripping, repairing caulk, and installing new screens can help temporarily, but in many cases, upgrading to new, well-sealed windows is the most effective long-term fix.

How to Inspect Your Windows for Pest Entry

To pinpoint the problem, start by:

  • Checking all screens for holes or loose edges
  • Looking for visible gaps between the window sash and frame
  • Feeling around the edges for drafts (flies can use the same pathways as air)
  • Inspecting caulk and weatherstripping for wear or cracking
  • Observing where flies tend to appear most often—it might be near a specific problem window

Easy Fixes for Immediate Relief

If you can’t replace your windows right away, there are steps you can take to reduce flies getting in the house right now. Patch small holes in screens with a repair kit, apply fresh caulk to visible cracks, and replace worn weatherstripping. Keep windows closed during peak insect activity (usually early morning and late afternoon) and use natural deterrents like citronella near entry points.

When It’s Time to Upgrade

If you’ve done all the repairs and still find yourself swatting flies daily, it may be time to consider new windows. Modern replacement windows are designed with tighter seals, durable frames, and built-in screen systems that make it much harder for pests to sneak inside. As a bonus, you’ll also get improved energy efficiency, noise reduction, and curb appeal.

Professional Help for Lasting Results

A skilled installer can spot window issues you might miss, from tiny frame shifts to improper sealing. They can recommend whether repairs will suffice or if a full replacement is the smarter choice. For information on window performance and sealing standards, Energy.gov provides a thorough guide on what to look for in quality, airtight windows.

Take Control of Your Home’s Comfort

Flies aren’t just annoying—they can carry bacteria and contaminate your food. By addressing the weaknesses in your windows, you’re not only stopping pests but also improving your home’s comfort, efficiency, and value. If you’re tired of dealing with flies getting in the house, a close look at your windows could be the first—and most important—step toward a bug-free home. Contact Friendly Windows to learn more!