in calcium dust - they should be "dusted" 
I put my crickets (or any feeder) into a quart size deli or yogurt container, put in about 1/4 tsp dust, gently twirl, then I put a strainer over the top, turn over and shake out any excess dust.
How old is the cham? He does not need to dust everyday and he should also be using a good multivitamin dust (Rep-Cal herptivite is one) but not at the same time. Set up a regular schedule so he can stick to it. There can be trouble in OVER supplementation as well. The older the cham gets, the more you should rely on properly gutloaded crickets as veiledbrian pointed out. The dusting is not the magic bullet to keeping the cham healthy and well fed feeders insects are important. Chamnews has some excellent article on supplementation you might want read. Go to this link and look under NUTRITION section.
ChamNews
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Chameleon Help & Resource Info
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