I am a pest control tech and a client of mine has been trying to get rid of a colony of ants in his front yard for multiple years now. He's had various pest control companies over the years. I tried spraying pyrethroids (Lambda-cyhalothrin) last year and I ended up going back four times and was still unable to get rid of them. It usually only takes one good spray to get rid of a regular ant hill if you spray enough pesticide that it can soak deep into the nest. In this case though, the ants are very spread out through his lawn. Hopefully these pics work... This is an example of what his lawn looks like. Except his entire lawn is like this, not just one or two areas.
I sprayed again in May this year. I sprayed the hell out of everything with a different pesticide (permethrin). I put in a rod ~8" into the ground and then sprayed in the hole every three or four feet squared throughout the entire lawn... And they are still there a week later! Even more of them maybe.
I was wondering if you guys had any other ideas for controlling these ants in this guys yard as he has spent hundreds of dollars trying to keep his lawn from looking like this every year. Also, why isn't the pesticide working? Is it possible that the ants have built up a resistance to the pesticide as they have been exposed to pyrethroids for so long? Do you think there are multiple queens or just one queen here?
His lawn isn't that large, maybe 40 ft squared. I live in Calgary, AB, Canada.
Any help would be appreciated! Also, I know some of you might not like the fact that I'm killing ants but let's try to keep this thread on topic and if you'd like we can have an ant ethics thread somewhere else.