Note: Please see my article Product Review: Gel Based Water Sources for House Crickets for additional information on cricket-keeping.
According to studies carried out at the Bronx Zoo, house crickets, Acheta domestica, should be allowed to feed for at least 48 hours before themselves being offered to captive reptiles and amphibians as a dietary item. This time period allows the crickets to absorb nutrients that will, ideally, offset their naturally poor ratio of calcium to phosphorus (which should, in most situations, be 2:1).
Chick laying mash, trout chow and baby cereal can all be fed to crickets, but none are formulated specifically for these insects, and each has disadvantages. When feeding crickets in public collections or at home, I now rely exclusively upon commercial cricket foods. The following products are all very well-accepted by these perpetually hungry little beasts, and the nutritional profiles of the diets (including calcium content) are based on the latest available research:
Ziegler Monster High Calcium Cricket Food
As has always been my practice, I add a bit of Tetra-Min Flake Fish Food to the commercial cricket foods. Both are consumed ravenously, and the wide variety of ingredients in the flakes helps assure that the crickets are receiving a healthful diet.
In addition, I add to their diets the powdery residue left at the bottom of oatmeal, wheat germ, nut and whole grain cereal containers. Oranges, yams, kale, carrots and other fruits and vegetables should also be provided on occasion, but only in amounts that are consumed quickly, lest mold develop.