From: James R. Baker and Stephen B. Bambara, Extension Entomologists
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. The biology is unusual in
that these scales reproduce in late summer and the tiny new
scales overwinter on the twigs and stems (most of the soft scale
insect pests of ornamentals reproduce in May or early June). 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.
These scales are preyed upon by numerous parasitic and predaceous
insects (including a predaceous caterpillar!). 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. If the tree is small enough to be sprayed with
insecticide, the next few weeks would be a good time to spray as
the nymphs are exposed on the stems. It is recommended that
infested trees be sprayed with Orthene, diazinon, Sevin or Mavrik
on the next warm, sunny day. Copies of Ornamentals and Turf
Insect Note No. 41, which contains information on sooty molds, are
available in the county Extension centers in North Carolina.
Web page last updated on October 13, 1997 by Stephen J. Toth, Jr..
