they pretty much feed constantly and need a regular, fresh supply of food. Some cut back a little in order to keep them from growing too quickly but due to my Saturnid rearing I am in the habit of alwasy supplying lots of clean, fresh food (plants, not chow
)
I know most folks grate it but I find it can dry out quickly and, as you have found out, gets eaten quickly as well. I have always sliced it into strips (say 1" x .5"
They climb all over it and many can feed on one chunk. It lasts long, won't mold if you have good circulation and keep an eye on it. I raise the "floor" by placing overturned plastic egg cartons on the bottom and then put a piece of plastic canvas on top. When they are young the poop falls right thru keeping the floor clean. I do not cover the tank at all once they are about .5-1" long. Obviously you can't use the pc when they are TOO small or they will fall thru! LOL! I might have a pic somewhere I will try to dig it up and post.
I am sure others do it differently but this is what works for me 
lele
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0.1 veiled - Luna
0.2 house geckos - Gaia & Tia (MIA 
0.2 felines - Kyndra and Líta