Mealworms are a beginning staple for me as they
are available in small sizes, the move around, and
they are easy to breed. I try to stick with newly
or recently molted ones and once the babies start taking
them I usually dust them with vitamin/calcium powder.
I also feed the mealworms lettuce and apple so they
get a little gutloading.
I also try rolipolis (sowbugs/pillbugs)and have a mini
compost pile going in a critter keeper made up of peat
moss, leaves and bark filled with rolipolis and small
worms I have found. I have spent a significant amount
of time collecting rolipolis, as many small ones as
possible, so hopefully I'll have a supply through most
of the winter. I only feed them the smallest ones I
have as I've found that hatchlings have a difficult time
chewing larger ones. They manage to kill and mutilate
them, but then spit them out.
I also try earthworms, although if they are too big and
too active they can intimidate young babies, so I'm trying
to collect the smallest ones I can find out of another
compost pile I have going.
As they get a little bigger and are eating well I occasionally
offer small crickets.
Thanks to PHratz for reminding me about lobster roaches, I
do have a colony going but haven't tried the baby roaches
with hatchlings yet.
As others have mentioned, its hard to depend on one single food source to start with, because some who won't respond to mealworms, might respond to rolipolies or earthworms.
I have some larger clutches where most of them are eating but one or two are not. I started marking them this year so I could keep track and I've got a couple that I'm going to try and get a little baby food chicken in their mouths if they don't start eating soon, although I don't usually start worrying too much until they are 3-4 months old.
I usually start adding a little salad after they have
been eating bugs well for a few months.
I eat bagged romaine salads everynight and I save some to
distribute a leaf or two to the babies that are inside
for the winter.