I'm cross-reposting this to alt.home.repair, where it will be seen by
many more people that the original groups it was posted to
(alt.consumers.pest-control, misc.consumers.house).

(I for one have no suggestions for the control or eradication of these
flies)

techman41973 wrote:

I live in Northern California, for years, I've had a locallized swarm
of flies in my garage that are only around in the daytime hours, near
a conventional-sized door that leads into my backyard (I keep this
door open for various reasons - laundry access etc.). In the evening
and night they disapear. The garage is extremely clean. I have no idea
what is attracting them, especially when they leave when its no longer
light out.

I tried fly paper, which doesn't work.
Wondering if anyone else has some constructive ideas
Thanks