They are white and translucent gross looking larvea 1"dia x 3-4 " long.
Large white larvea found in a sugar maple 1" dia. X 3-4 " long. What are they going to become?
St. Louis County Minnesota
We can't tell what the larvae may become without seeing them, but they are probably a kind of wood boring insect described in the following bulletin. Although the bulletin was prepared for Oregon residents, most of the information also applies to Minnesota.