I don't want to harm the earthworms and other beneficials but the grasshoppers got into the greenhouse and are eating everything. Any tips would be appreciated

NO boric acid! That'll kill everything and nothing will grow in soil treated with boric acid.

Use the diatomaceous earth (Howard prefers Soil Mender, but there are other brands out there for organic gardening uses. Don't use the pool filter variety, that is a lot different.)

Another product he recommends is a slurry of finely ground kaolin clay sprayed along with orange oil or garlic pepper tea. There is a commercial mix called Surround WP if you don't want to mix it yourself.

There are a various treatments that will get rid of the grasshoppers that you'll find in the Library (here's the grasshopper link: http://www.dirtdoctor.com/organic/garden/view_question/id/28/)

Ginny ,try to find someone who has a chicken to loan out.