Muscadine grape problem

[Francis Barnswallow]

Not sure if anyone is familiar with growing muscadine grapes but I've got a problem with them for the second year in a row.

I've got 3 large muscadine grape plants (trees if you will) and they grow just fine but then drop hundreds of semi ripe grapes to the ground. At first I thought it was squrriels but there's no damage to the grapes that have fallen to the ground.

Could heat have something to do with this..........similiar to blossom drop?

[Francis Barnswallow]

Actually upon closer inspection of the grapes, I've noticed tiny puncture marks in the grape skins. It's gatta be squrriels.