In reading more about acorn weevils, I stumbled across a float test for acorns. If the acorn floats, it most likely has been inhabited by a grub, because the grub eats the nut meat and lessens the acorn density. I took a handful of carefully selected acorns, that I believed were grub free, and put them in a cup of water.

Half of my acorns floated. I broke one of the floating ones open, and sure enough, there was a grub inside. Hm. I also read that squirrels will leave the grub infested nuts, so when humans are searching the ground it will seem like the weevil infestation is total, but really the whole nuts have already been found and buried. Learn something new everyday.