Cluster flies are a lawn problem, not a kitchen problem
This is the fact that surprises most property owners. Cluster flies parasitise earthworms and develop in soil, so they have nothing to do with garbage, drains or food. Large lawns, pasture and open fields produce them, which is why rural Hastings, Prince Edward County and Frontenac properties see them and downtown Belleville largely does not.
- Cleaning will not reduce them
- Larger, darker and slower than house flies
- Associated with attics, wall voids and upper rooms
- Common on acreage, farms and cottage properties
Read the sunny wall
On a bright October afternoon these insects bask on warm siding before working their way inside. The south and west walls crawl while the north wall stays quiet. That is not a coincidence — it tells you exactly which walls to prioritise when you seal.
- Check south and west elevations first
- Look under fascia, soffits and siding laps
- Watch window and door frames
- Note which rooms fill up in January
Flies at the window in January entered in October
Insects appearing at upstairs windows in midwinter did not just get in. They entered in autumn, settled in a wall void or attic, and woke up when warm sun or indoor heat roused them. By then the entry points are behind finished surfaces and the opportunity to exclude has passed.
- Vacuum rather than spray indoors
- A window fly trap at the sunniest window helps
- Do not fog wall voids
- Record the rooms affected for next year’s sealing
Boxelder bugs and stink bugs read the same wall
If the basking crowd is red-and-black rather than grey, you are looking at boxelder bugs. If it is a shield-shaped brown insect that smells when crushed, it is a brown marmorated stink bug. All three respond to the same exclusion work, so one sealing pass handles the lot.
- Boxelder bugs: black with red markings
- Stink bugs: shield-shaped, marbled brown
- Neither damages the structure or bites
- Crushing stink bugs stains and smells
Timing is the whole job
Exterior treatment and sealing work in late August and early September, before the insects move in. The same visit closes the gaps that mice use a few weeks later, which is why this is the most valuable service call of the Eastern Ontario year.
- Book exterior work for late August
- Seal soffit, fascia and siding gaps
- Repair screens on attic and gable vents
- Combine with autumn rodent exclusion