When I moved into my house, the backyard was infested with earwigs. You couldn't move something in the yard without at least 5 earwigs crawling out from under it and we found at least 2 in the house every day. Part of it was that there were a lot of weeds in the back yard and I'm sure getting rid of them helped, but the best thing I did was to put about an inch of vegetable oil in the bottom of plastic cups and place them around the yard. They crawl in, get covered in oil and can't climb out. I put 6 cups around the perimeter of the lawn. I dug a small hole so that the cups could sit down in the hole a bit and not fall over. After one week, each cup had about 100 earwigs in them (I also got beetles, spiders, roaches and other bugs)! I emptied them out, replaced the oil, and got similar results a week later. The third time, I got a lot less and it took longer for any of the cups to fill up. Now, I rarely find earwigs in the yard and almost never in the house. I'm not totally sure how much of it was the time of year, how much of it was getting rid of the weeds and how much of it was the oil, but I'm sure the oil killed thousands of them and protected a lemon tree we have out there.