I have a well established lawn and live in Massachusetts. Recently, I have noticed hundreds of little 'mounds' of dirt that seem to have pushed up or 'been' pushed up. They seem too small for rodents but don't know. The dirt is 'lumpy' (like its been worked by something. We have had a slight frost but nothing severe and the grass is still growing (mid October). I noticed these last year as well. I also noticed a HUGE swarm of flying ants last week that seemed to be eating the grass blades. I killed them with flying ant spray. I don't know if its related. Any ideas? Thanks.