Well the good news is they do not have to have cricket or bugs in general, cresties will do just fine on CGD again they don't have to have bugs.
In captivity IMO some become lazy do not want to chase and don't like the jumpy type of bugs, lot of thing are illegal in Canada so you might not find Dubia, you can offer Phoenix work but go easy on that they are very fatty.
Basically if your crestie does not want cricket and you can't find dubias (which you should feed in a dish 4x3 dish) the best thing is just to feed CGD.