Try using forceps and pressing the night crawler or hornworm up against his mouth. Don't feed him pinkies so often though. You could try breeding roaches, offering mealworms or superworms once a week. Breeding your own feeder fish (Guppies, minnows, shiners) offered once a week. Just don't buy them from the pet stores, they are full of parasites caused by high ammonia, nitrite levels, and poor conditions (Hence 'feeder fish').

If you do buy feeder fish to breed and you buy them from a pet store. Flush them of parasites with a parasite medicine and keep the water clean (Changed ever 2-3 days). Parasite medicines: Maracide, Jungle Labs Clear tablets. Preferably buy the feeder fish from a reptile shop or reputable fish store, then you don't have to worry about parasites.

He's just a picky eater, keep supplementing his crickets for the time being so at least he's getting some other nutrients besides just what is found in crickets until you can provoke a feeding response out of a earthworm. The problem with just putting the night crawlers in the tank and leaving them alone is they'll just burrow into the substrate. You're going to have to tong feed them, set them in a dish, or feed him in his water dish.

Honestly hornworms are a little bit ridiculous even if he did feed on them, they have great nutritional value. $15-17 for a bin though, really? I mean get him to eat red wigglers or night crawlers and only offer hornworms for like a special, special occasion. These frogs are eating better than some humans... I guess if you got the money, hey why not?

Go to Samurai Japan Reptiles site, they sell 'Pacman Food' on there. Add water and like 2 teaspoons of the formulated diet and you roll into a ball to feed. I heard it's a little bit pricey, but it could be offered as variety since he's only eating crickets.