I have laid short peices of garden hose under the plants around the garden. Then you walk around with a bucket of soapy water and knock the earwigs out into it. I had never heard of adding ammonia.
Back in the day they used rolled up newspaper and threw them in to a bucket of kerosene and ignited it, but that's not environmentally prudent.
Also a friend of mine uses plastic tubs (like cream cheese comes in) and pokes some holes about half way up just big enough for the earwigs to get in. She puts some sort of soy sauce mixture in it and they drown in it. I'll try to get her recipe.
If you have kids or pets please don't use earwig bait. It's terrible stuff and sometimes is attractive to songbirds as well.
Yuck on earwigs.