If you use crickets, some will jump out so you end up doing both.
Roaches, supers. silks, and horns tend to stay in the bottom of the cup, where crickets climb naturally. The result is without movement the cham will ignore the food. A trick is to put some crickets in the bottom to teach the cham to look into the bottom.
Until they learn, worms are best served on the cup climbing surface, a branch, or on the screen.
CHEERS!
Nick