Disappearing snowdrop bulbs

[Hils54]

I’m hoping experienced growers can help as I can’t find the answer elsewhere.
I have bought numerous named Galanthus bulbs both in person and online. I have potted them up as instructed in black plastic mesh pots and with recommended compost. Some I’ve plunged into the border, some not. They’ve grown on happily but then once they’ve died back and I’ve come to repot in fresh compost, I’ve discovered that in several (too many!) pots, the bulb has disappeared, leaving only an empty papery ‘husk’. This tends to be the ‘free standing’ pots.  I must have spent a small fortune on disappearing bulbs. I’m obviously doing something wrong, but can anybody tell me what, please? It’s disheartening to say the least.

[Gail]

Has there been any sign of disease while in leaf? Botrytis galanthina is more common in wet seasons.
Otherwise it could be the dreaded narcissus fly/swift moth larvae finding them? (I am personally convinced that swift moths can read labels and target your most expensive plants!) Once they have finished flowering moving pots to a shady position or covering with light fleece will reduce attacks.
Or maybe they have dried out too much during dormancy and shrivelled? Mesh pots tend to dry out quicker but the plunged ones should have been okay...

[Alan_b]

The narcissus fly larva will eat the middle out of a bulb but leave the outer husk for protection.  It will then pupate into the adult fly, which will fly off in spring.  A swift moth larva will eat the roots and the bulb, but will sometime move on, leaving a half-eaten bulb which may recover.  It attacks from the outside so is unlikely to leave a husk. 

I used to cover my pots with a very fine mesh netting from May to October.  I also had a raised bed for snowdrops and covered the entire bed.  This seemed to work.