Flies & Mosquitoes
Cluster Fly
Slow, sluggish flies that pack into attics and wall voids each fall, then appear on sunny windows. One of the most common fall pests in Sudbury homes.
Quick facts
- Size
- 8–10 mm
- Colour
- Dark grey with golden hairs on the back
- Active season
- Move in during fall; appear on warm winter and spring days
- Where found
- Attics, wall voids, upper rooms, sunny windows
How to Identify
- Slightly larger than a house fly
- Golden-yellow hairs on the back (thorax)
- Wings overlap at rest; slow, clumsy flight
Signs to Look For
- Many flies on south- and west-facing windows
- Dead flies piling up on sills and in light fixtures
- Buzzing in attics or walls on warm days
Why It Matters
- Do not breed indoors or spread disease like house flies
- Can leave spots on walls and curtains
- Return in large numbers year after year
Prevention Tips
- Seal gaps around windows, siding, soffits and vents by late summer
- Repair torn screens
- Vacuum live and dead flies rather than crushing them
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