Reduced Growth Associated with Infestations of Douglas-fir Seedlings by Cinara Species (Homoptera: Aphidae)

Abstract

Aphids of the genus Cinara are capable of causing serious growth reduction of Douglas-fir seedlings. Growth of infested seedlings may be only one-fourth to one-half that of uninfested seedlings. The aphids are easily controlled by injecting demeton around the base of the seedling. The presence of ants to clean up excessive honeydew is shown to be beneficial for the aphids.