You don't say where you live. I suggest you contact your local extension service as they would know what pests are active in your area right now.
If they don't recommend something that is environmentally friendly, get back in touch with us or check out these sites.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.