no, cresteds can't live off of crickets alone. a diet of just crickets would cause mbd and likely other nutritional deficiencies. that's why it is so important to get them on the cgd--it is a complete diet that contains everything they need. while cresteds are hardy little geckos they do have nutritional requirements that must be met--lucky for us we have cgd to make that easy.

the powder that you dust crickets with like herptivite and reptivite isn't the same as cgd. if you want you can lightly mist the crickets first and them dust them--that will help it to stick better without such a mess. when you dab some on their noses you can hold up a little spoon with more on it or just use your finger and let them keep licking. after a few times of doing that they should start eating it on their own out of the dish.