I've really noticed that Horned frogs take a little while to get used to Dubia, especially when the frogs are young. I've tended to use crickets and nightcrawlers as staples when the frogs are young, and then introduce Dubia over time. The freshly molted Dubia seem more palatable - Dubia are a bit "spikey". Dubia are great feeders, although I find that they can be a little inactive and don't trigger a good feeding response in some animals - my toads for example. Dubia freeze when alarmed.