Extension Entomologists Time to Treat Big Scales on Magnolias and Tulip Trees Magnolia scale and tuliptree scale are among our largest scale insects and are sometimes quite damaging to tulip trees and magnolias. Although they are in different genera, these scales are quite similar in appearance and biology.
Male scales appear in early summer and mate with the females.
The females swell considerably with eggs during the summer, but the eggs hatch as they are laid so that it appears the crawlers are born rather than hatched. They have one generation per year. Infested trees may become sticky with honeydew excreted by the scales and black with sooty mold fungi which grow in the honeydew. The tree may be weakened overall with sparse foliage and dead branches, or the trunks may be distorted because the scales have killed the leader branches over the years. Most homeowners object to the honeydew as well as the wasps, flies and bees which are attracted to the honeydew.