cocoon vanished

[svake]

this morning i have many silk worm (around 6 - 12) at stage 3 in 3 chest after 3 hours all cest are empty what appened? (obviusly cest are protected by wall and in my claim zone so noone take it)

[Jeff]

Did you remember to give them leaves? (they have 4 stages)

[svake]

ok im an idiot sorry
dont know why i think that at 4 stage they dont need eat to transform in cocoon