They aren't necessary for a lawn.
There's a natural thing you can use using chewing tobacco, non phosphorous detergent and antiseptic mouthwash. Something that's poisonous to the bugs but not to the humans and animals.
There's a site called
www.jerrybaker.com that has some good recipes on it for this stuff. Most of it's just simple stuff you have around your house. You just have to make sure if you're using it on plants that you're going to eat, you wash the fruit/vegetable well.
He's even got some recipes that call for 1/4 to a cup of human pee. So, you can use everything.
Shael