Just throwing stuff out at random here, because I use chemical controls, but perhaps diatomaceous earth to suffocate/dehydrate the larvae?

Are honeybees feeding on your asparagus?

I'm with ltilton. I used Seven last year (first year with these beetles and they haven't shown up this year) and they were gone in a day. Asparagus is a long way from flowering before harvest time. I suppose one could arrange a plastic tent over the aspargus to prevent drifting while spraying. I used a kitchen spray bottle.

Asparagus beetles can usually just be hand picked off the ferns and squashed. They are easy to see and no chemicals needed. In bigger gus patches some of us use a vacuum to just suck them off.

Dave

I/powders that harm bees, even wait till late afternoon, the bees will be home for the night.

Thanks everyone for replying to my problem. I finally decided to spray them with a combination of lemon juice, vinegar, and dish soap. It took a full day, but it killed all the larva and most of the beetles. I cant use Sevin as some of you suggested. any small amount could get on a bee and they carry it back to the hive. Dont need that. Thanks all for your help.