New infestations originate with eggs laid by the adult female moths, one generation per year.
May. Eggs hatch about the time new shoots emerge from buds and the tiny larvae immediately begin to bore into the fresh young shoot tissue. The larvae feed and grow within the developing shoots through May, June and July causing tip growth to die back beyond the feeding site. When feeding is completed, the full-grown caterpillar leaves the shoot to crawl down the trunk. On the side of the trunk, just below the soil line, it forms a white, paster-like silken cocoon for pupating. Winter is spent in this stage with adult moths of the southwestern pine tip moth emerging the following spring on return of warm weather.