Sometimes they won't eat dry food or the high calcium veggies, so I just blend them all together with some fruit. The calcium hasn't killed them, so I don't think it's a problem. I use a lid to a glass jar that I just leave in there. I spoon about 1/2 cup to 3/4 of a cup of the stuff into the lid. They eat it off of eachother if it gets on some of them.
EDIT: the crickets like it too, but they won't eat it (for me anyways) unless I put an extra fruit in it. Also, blend the fruit first.