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.
http://www.ceinfo.unh.edu/cesites.htm
If they don't recommend something that is environmentally friendly, get back in touch with us or check out these sites.
http://www.gardensalive.com/index.asp?bhcd2=1075148306
http://www.extremelygreen.com/
http://ourgarden.pair.com/mars/BRProductInfo.htm
http://www.planetnatural.com/tableofcontents.html
Newt
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.