What is eating my beans?

[Digeroo]

Sowed some wizard broad beans for overwintering and something is eating them.  They are covered thowith bottles so not mice or voles or squirrels all of whom eat the whole bean.  This just eats the root and seems to burrow through the bean as some have holes in them.  Not met this before.  Only about 1/3 have survived.  Though a few are sprouting a new root so might still happen.   
Any suggestions please. 

[Digeroo]

[Robert_Brenchley]

Slugs?

[johhnyco15]

if they are little u shape holes its proberbly pea and bean wevil