Offspring of the dung beetle,Onthophagus gazella(F.), declined significantly in size and number as a result of increased parental density during nest construction. The parent beetles' ability to utilize the manure fully also declined with increased density. Offspring reared from brood balls provisioned with manure during the late stages of a nesting period were significantly smaller than offspring reared in balls provisioned during the early stages. Brood balls provisioned with manure of lower protein content yielded significantly smaller adults compared with adults from the stock manure. The role of these factors in beetle size determination and in the ecology of manure pats is discussed.