Most eggs are found on the nutlet tips. The greenish-white to white eggs change to pink or red before hatch. Each female lays 50 to 150 eggs during her 5- to 8-day life.

Casebearer eggs hatch in 4 to 5 days; young larvae craw lto nearby buds below the nuts to begin feeding. The white empty egg shell remains on the nut. After feeding for a day or two on a bud below the nut cluster, the tiny larvae enter the pecan nut, often tunneling in at the base.

Silk and black frass (excrement) are often visible on the outsides of infested nuts. Larvae feed inside pecan nuts for 3 to 4 weeks, depending on the temperature. They are olive gray and reach a length of about inch. Full-grown larvae pupate in the pecan nut; adult moths emerge about 9 to 14 days later.

The pecan nut casebearer completes several generations each year. Adults of the overwintering generation emerge in April and May and lay eggs on pecan nutlets soon after pollination. First-generation larvae mature to moths, which lay second-generation eggs in grooves on the tips or bases of nuts, or on buds. Second-generation larvae attack the nuts in midsummer about 42 days after nut entry by first-generation larvae.