Frozen food?

Hi! I've had my juvenile axies--about three or four inches long--for a few weeks. When I first got them, I bought some frozen daphnia, and they were given that for the first week home. However, I barely saw them eat it, and most of it just ended up on the bottom of the tank. After that I started feeding them earthworms from my yard (no pesticides or herbicides used), and have kept doing that. But this week, the soil outside is too dry and cold for me to find any earthworms.
Until I can get some store-bought earthworms, what should I do? I still have lots of daphnia, but I'm afraid it will get ignored and just end up making a mess again. Is there a special way to feed axolotls frozen food? They were both fed half of an earthworm three days ago. I might be able to get store-bought worms tomorrow.
Thanks!

If you're in Portland, you can go to most large Fred Meyer's or Walmarts. They will have Canadian Nightcrawlers in a fridge in their fishing section. They're very easy to find, so don't bother with frozen food. You can try bloodworms, but since earthworms are so easily found in Portland, don't bother. I can PM you some known locations that for sure carry them if you need them. Just wait till tomorrow to get earthworms. Better than screwing up water quality. They can wait a day. I'd keep a container in your fridge to make sure you have some if you can't find any in your yard.

Also, with earthworms found outside... I put them in a tupperware of dirt with small holes in the lid and store them in the fridge. I can store up for 200 in the fridge and they last quite a while.

Awesome! Thank you.