re: Flies on Patio

I had a patio fly issue for a bit. There was a cavity where the small gap b/n the house slab and patio slab met. I noticed some flying from there and sprayed the crap out of it with insect poison , then filled it in with sand. Fly problem went away. Must've been breeding there. Later learned there was a slow pipe leak there FWIW. It fed the problem by providing moisture. Luckily close enough to edge of slab not to cost a fortune.