grubs!

My husband has noticed several large grubs in our compost,- bigger than japanese beetles, but similar coloring. We have been tossing them out for the birds. Our questions:
1. Does anybody know what they are? We have been composting for many years and more intensely since retiring.This is the first we have seen these grubs.
2. Are they harmful or helpful to the compost?
TIA..Marty Roseen
PS. I'll tell him to let me know next time so we can get a picture....

Grubs grow into beetles. In the compost it is 'helping' because it eats compost and poops out beetle grub manure which will be closer to the form a plant can absorb. Question is what beetle it grows into, and what the adult beetle eats.

Thanks for the quick response. We'll leave them in and pass that information on to our son for his compost. Here is the picture, so hopefully someone can tell us what they grow into.