If you solely feed crickets, yes they should be dusted every third feeding or so. Use a high quality vitamin and calcium product like Herptivite plus calcium with VitD powder. As the prior poster stated, variety is always best. If you had to feed only one food, nightcrawler pieces would be the best as it is the most nutritionally complete food and does not require supplementation prior to feeding. Myself, I would avoid pinkies...except as a rare treat for a very thin animal.