4 Dubia per cham every feeding. 8 Dubia(total) per feeding @ 15 feedings a month = 120 Dubia a month is your minimum replacement rate. 120 a month replacement rate is nothing for a healthy colony. Im feeding two adults as well, when I began my colony I also bought a few hundred to feed off while my colony developed. It timed out perfectly, my colony hit full replacement rate when I was about 3/4 of the way through the Dubia I bought for feeding off.