Where are the black flies in my house coming from?

Answered by Jason Smith

Where are the black flies in my house coming from?

Black flies in your house are most likely cluster flies. These flies are common household pests that tend to show up in bedrooms and on window sills during the late fall through early spring months. They are large and black, and their presence can be quite pesky.

Cluster flies get their name from their habit of clustering in large numbers inside attics. They prefer dark and secluded areas, making attics an ideal location for them to gather and overwinter. As the weather starts to cool down, cluster flies seek shelter and warmth, often choosing homes as their refuge.

So, how do these flies make their way into your house? There are a few possible entry points they might use:

1. Cracks and gaps: Cluster flies can enter your house through small cracks and gaps in windows, doors, and other openings. It’s important to seal any noticeable gaps to prevent their entry.

2. Chimneys: If you have a chimney, it can serve as an entry point for cluster flies. They may enter through the chimney and find their way into your living spaces.

3. Vents and exhaust fans: Cluster flies can also use vents and exhaust fans as entry points. These openings provide easy access for them to enter your home.

Once inside, cluster flies tend to gravitate towards windows, as they are attracted to natural light. You may find them buzzing around window sills or congregating on curtains.

It’s worth noting that cluster flies do not breed indoors. Instead, they lay their eggs in soil, typically in grassy areas, and the larvae develop as parasites on earthworms. As adults, they seek shelter in buildings to escape harsh weather conditions. So, if you’re finding cluster flies in your house, it’s likely that they have already found their way inside from their overwintering sites.

To prevent cluster flies from entering your home, consider taking the following measures:

1. Seal cracks and gaps: Inspect your windows, doors, and other openings for any cracks or gaps. Seal them properly to minimize the entry points for cluster flies.

2. Install screens: Use window screens or mesh coverings to prevent flies from entering through open windows.

3. Chimney caps: Install chimney caps to keep cluster flies from entering through the chimney.

4. Proper ventilation: Ensure that vents and exhaust fans are properly screened or covered to prevent flies from entering through these openings.

5. Regular cleaning: Keep your home clean and free of food debris, as cluster flies are attracted to food sources. Regularly clean areas where flies tend to gather, such as window sills.

If you already have cluster flies in your house, you can try the following methods to control their population:

1. Vacuuming: Use a vacuum cleaner with a hose attachment to suck up the flies. Dispose of the vacuum bag or empty the canister promptly to prevent their escape.

2. Fly swatters or traps: Use fly swatters or sticky traps to catch individual flies. These methods can help reduce their numbers but may not eliminate the problem entirely.

3. Professional pest control: If the infestation is severe or persistent, it may be necessary to seek the help of professional pest control services. They have the expertise and tools to effectively manage cluster fly infestations.

The black flies in your house are likely cluster flies, which gather in large numbers inside attics during the colder months. They can enter your home through cracks, gaps, vents, chimneys, or other openings. Taking preventive measures to seal these entry points and implementing proper sanitation practices can help minimize their presence. If an infestation occurs, various methods such as vacuuming, fly swatters, or professional pest control can be used to control their population.