As long as you are sure the area has not been sprayed you should be ok. This was a topic a while back. Do a search for the "bug bazooka" and you will get onto a good thread. I'm used to the term field sweepings, but I like grass fishing better, clever. Its a nice way to give your frogs some variety. The spiders, caterpillars, flies, gnats, true bugs, and such are all great micro fauna. Have at it. And if you need a good source for insect nets or field sweeping supplies try a company online called bioquip.