Posted: 07/09/2016 at 19:29
We don't get many here (hope I've not talked them up) but one house I lived in used to get a lot of flies come indoors in the summer months. We found that a Vapona Pen was very effective. It's a clear liquid in a sort of felt tip pen - you draw it around the edge of each window pane - you can hardly see it, but when the flies walk over it, and they usually do, it doesn't take long for whatever the stuff is to kill them. You just have to sweep or vacuum them up each day.
I liked it because it was invisible and I wasn't spraying noxious stuff into the air.