Teledyne plans to sell some insurance lines.

The Los Angeles-based manufacturing and insurance company said it plans to divest its commercial casualty insurance business, which is headed by Argonaut Insurance in Menlo Park, Calif. Subsidiaries selling auto and homeowner insurance would not be affected. Argonaut reported about $315 million in premium income last year--about one-fourth of Teledyne’s total insurance income, which in turn constituted about a third of the parent’s total revenue. Argonaut units lost money last year, as did much of the commercial liability industry.