I had avoided damage to my asparagus beds in prior years but this year was different. Almost all of my fronds have significant damage as the outer skin was eaten away.
Fortunately there is some new growth so all is not lost. I started, too late, spraying with Captain Jack’s Dead Bug but will be more attentive next season. You should inspect the area for a natural predator (Tetrastichus asparagi, a parasitic wasp) before spraying.
There are two beetles that cause this damage:
Here they are together and you can see the damage done to the asparagus frond.
The asparagus beetles larvae overwinter in leaves and frond debris, one of the most common organic control techniques is to remove all leaves and other vegetative matter late in the fall and lightly till the top soil to disturb any larvae that might be in the surrounding soil. After doing that, I will spray the crap out of them next spring; Captain Jack’s Dead Bug is an organic pest spray.