today was our garbage day and when I went out to put my cans back in my yard noticed they did take mattress from next door but left all the other garbage.

Anyways a grey truck just pulled up with a small triangle on the side. a guy had a large sprayer and sprayed all into the garbage and around the cans.

Would the trash collectors not pick up neighbors trash due to insects?

Then I'm thinkin oh great what ever little critters are there will probably wander my way.

edited to add, i called dept of waste and the guy said there was a pest infestation.

I'm thinking couldn't have been just flies ....

Probably bed bugs.  I doubt it was for roaches.

The city actually has policies and procedures for cockroaches, due to the infamous Emmett Street roach house. I'm thinking that chances are pretty good that this is what it was about. Also because I don't think bedbugs hang out in the trash they hide in the walls and furniture from what I've been hearing on the news.
It's interesting, a lot of what the city doesn't do right is often just because nobody working for the city knows to do it. Somebody working for government during the heydey of civil service, the 1960's, retires and with them goes the "institutional memory". We were forced into a cockroach policy in the 1980's and it looks like it is still working.
I hope it is roaches and not bedbugs because we already had roaches, we don't need another thing, plus roaches at least don't bite you.

Of course, it could have been maggots, it has been warm and if I were working a garbage truck I wouldn't want to handle that either.

I knew someone who became infested with cockroaches when their neighbor fumigated their home. Let's hope they are only maggots. Cockroaches are hard to kill and carry suitcases!