It depends on the species, sex, age, and particular mantis how often I feed. Usually I feed nymphs through sub adults once a day. At adults however many of the males will skip 1-3 days between eating. As for the females, well the little piggies would probably eat all that I offer and more, but I often feed then two days in a row and one day off. Since I'm not into breeding them I try to keep it easy on the pace they gain weight between laying ooths. Seems easier on the girls bodies to lay smaller ooths with longer stretches in between laying because of the more moderate diet, especially as they age.