They will eat crickets. Actually, crickets are much better because they have much more protein. Mealworm are good for putting a little weight on the guy, but nurishment wise, crickets are much better. My experience is that if you lizard gets hungrey enough it will eat almost any size cricket. If your lizard is not eating at all you may want to make sure that it is not sick. The gecko's are very sensitive the changes in their enviroment.