My son was grass this year. It was so easy and caused quite a stir at his school carnival. Everyone was snapping pictures with their cell phones!
I used heavy duty hair gel and then sprayed it with tons of hair spray. Then I sprayed it with green hairspray. I used the blow dryer to dry it quickly (we have early school) and then for some of the plastic bugs I hot glued them to the hair. Yep, I used my glue gun :) I tested it on the tips of his hair just in case it didn’t come off easily. I figured I could cut it off. But it did come off pretty easy. I think it is because the glue was mainly sticking to all the gel and hairspray and not his actual hair. Some of the critters I attached with fishing line. I tied it around the bug and then around a chunk of hair. I then added a glob of hair gel to act as glue so the knot wouldn’t come out or slip out of the hair. Both ways worked great. If I had had more time I probably would have done them all with fishing line.