I had a lot of mosquitos (gnats we called them) flying up and down in a column, every time I opened the door or window they invaded the place and I suffered bites. I then discovered an old spray can of 'Raid' and gave the column a blast came in and closed the door before the house stank. The next night another column appeared although now depleted, another quick blast from the can and now they are all gone, so now I can open the door or window without the risk of being chewed on, Hooray!