Sounds like you have a grub infestation. Do you have any signs of tunneling in your yard. Grubs bring moles and moles tunnel. I don't keep your species so I do not know if it can eat it, sorry!
That looks like what we texans call a tomato worm they get bright green.
A grubb is white with a tan head.And your tort. Can eat it but if it's a tomato worm no they can not .they eat the leaves and the leaves are toxic. So if you don't know witch is witch I wouldn't feed it .
I have some Great Plains Toads and farmers love them because their main food source is cut worms,wish I could figure out how to raise them for my toads.