Oh, I just remembered something! Look into the dubias for sure, but I know something else your Pacman Frogs can try. Earthworms!
Now, don't go to the bait shop and get some random earthworms. The bait shop is an unrealiable. There is no way of knowing what they put their worms in, and what parasite their worms have.
Go to Walmart. Yes, Walmart. and buy baby or adult Night Crawlers. Walmart has some kind of policy that they have to follow concerning a lack of parasites in their worms. Walmart worms are safe and realiable and offer a good combination of calcium and fat. Great and cheap! Many people on this site have fed their frogs on these worms for years, and I do not believe I have heard of one instance where a frog ended up with parasites from it. I think all that have tried it would recomend it.
Sad thing with Earthworms, though, is that you can't really breed them at home. They need temps that are warmer than the fridge, and colder than room temp. They will last pretty much forever in the fridge, though (it basically stops their metabolism).
Try one of those. If you dust them, it will increase the visibility of them considerably. Just let it warm in your hand afew minutes before feeding it to your Pacman Frog so that it can start "waking up". You want it to squirm a little.
Still check out the dubias, though!