What's eating my seeds?

[derf]

Somthing is eating my seeds. I planted french beans in pots in the greenhouse, after waiting 2 weeks for them to come up I had a little dig  in the pots and found that my seeds were all gone but the shels. Closer inspection revealed teeny weeny little grey caterpiller is the only way I can discribe them.  What is it? How can I stop it happening again? :'(  Please help?

[derf]

[Mrs Ava]

Could be that you had the compost tooooo wet for the bean seeds.  I have had similar problems with big seeds and have found that you are much better off using almost dry compost, watering them once, lightly, then not again until they have broken the surface, which with beans is normally just a matter of days.

Sow some more, you still have oodles of time.

[tim]

Oh, dear! - but they have to live - don't they?? = Tim

PS Haven't a clue - but all our runners rotted. Without grey things!

[allotment_chick]

Could be larvae of scarid fly (aka fungus gnat) - unlikely to have damaged the seeds enough to kill them off, but they feed on decaying organic matter.  
Might be worth a Google to find out more
AC

[Ceratonia]

There's a thing called a 'bean seed fly', whose larvae eat french bean seeds and look like maggots. Sounds like it might be this?