Plantings of Ceanothus griseus L. (also Ceanothus thyrsiflorus var. griseus L.) were invaded by a rare leaf miner, Tischeria immaculata (Braun). Adults appeared at the beginning of May and most flew between 1750 and 2400 h. Mating and egg laying started immediately and females laid an average of 35 eggs (range: 15–48). Eggs measured 0.12 mm by 0.08 mm, were translucent, and hatched to minute larvae which did not feed until 24 h after hatch. Larvae reared at different temperatures and moisture regimes performed best at 21 °C and 70% relative humidity. Frass was ejected through the oval trap door constructed at the initiation of the larval mine. Pupation took place anywhere within the mine but the adult emerged through a crescentic exit hole at the end of the mine.The principal enemy was a eulophid, Pnigalio flavipes Ashmead. Various species of spiders and a bird, Junco hyemalis L., preyed on adults. Emerging adults were also trapped and killed in spittle-bug froth.