close up of tuliptree scale

Female tuliptree scale (Toumeyella liriodendri)
Photo: Albert (Bud) Mayfield, USDA Forest Service, Bugwood.org

Updated: March 22, 2022

Key points

  • Tuliptree scale (Toumeyella liriodendri) is a native type of soft scale insect that can be difficult to manage as their waxy body covering shields them from predators and certain pesticides. Learn more about scale insect groups and biology on Introduction to Scale Insects.
  • This is a common pest of tulip poplar, magnolia, and a few other trees and shrubs and can cause stunting and dieback when populations are high.
  • Target monitoring and control efforts to the vulnerable crawler stage. Learn more about what to look for on Monitoring for Scale Insects

Appearance

  • Mature female covers are hemispherical, orange mottled with black (turning brown in death), and up to ¼” (6 mm) in diameter.
  • Male covers are elongated and white.
  • Crawlers are black.
close up of tuliptree scale crawlwers
Black overwintering crawlers and brown dead crawlers
Photo: John .A. Davidson, Univ. Md, College Pk, Bugwood.org

Common host plants

  • Primarily tulip poplar (Liriodendron tulipifera) and magnolia (Magnolia)
  • Various trees, including linden and basswood (Tilia), hickory (Carya), and walnut (Juglans)
  • Several shrubs, including red bay (Persea palustris) and buttonbush (Cephalanthus occidentalis)

Where to look

  • All life stages will be found on twigs and small branches.
  • Ants often protect colonies of this scale in order to feed on the honeydew. Examine busy ant trails on young host plants to see if they are tending a population of scale in the canopy.
  • Tuliptree scale on a magnolia branch producing drops of honeydew.

    Mature tuliptree scale on a magnolia branch producing drops of honeydew
    Photo: Chazz Hesselein, Alabama Cooperative Extension System, Bugwood.org

  • Adult Tuliptree scale cluster with alive dead adults

    Adult tuliptree scale cluster with dead individuals
    Photo: Joe Boggs, OSU Extension

Plant damage

  • Moderate to heavy infestations will produce large quantities of honeydew, which can attract other insects (mainly flies, wasps, and ants) and support the growth of sooty mold.
  • Heavy or prolonged infestations can cause leaf yellowing and shedding, plus twig or branch dieback. Young trees may be killed.

Honeydew and Sooty Mold

Life cycle

  • There is 1 generation per year in Maryland.
  • The crawler emergence period depends on temperature and can vary slightly from year to year. The approximate time to monitor for them is mid-September through October.
  • They overwinter on the bark as juveniles.

 

illustration of tuliptree scale life cycle
Tuliptree scale life cycle
Illustration: J.A. Davidson

Management

Refer to our general scale management recommendations for both chemical-based and pesticide-free options. When pesticides are warranted, a combination of dormant oil applications and the use of systemic or growth-regulating insecticides is the most effective approach. For large populations, scale suppression may require more than one year of intervention, and professional pesticide applicators will be needed to apply certain treatments. Mature trees should be evaluated by a certified arborist.

The brief crawler emergence period for tuliptree scale means that monitoring and treatment may need to occur in a relatively limited timeframe. 

Introduction to Scale Insects

Timing details for monitoring and pesticide use

Start monitoring for crawlers right before the expected emergence period. Since weather trends can shift date ranges, a more reliable prediction of timing can be made using Growing Degree Days and Plant Phenological Indicators.

Below
 is a refined estimate of egg hatch and the beginning of crawler emergence:

  • 3519 degree days

After the peak flowering of the Seven-son Flower (Heptacodium miconioides)

Seven-son pink flower
Seven-son flower post-bloom
Photo: Miri Talabac

Adapted from: Davidson, J.A. and M.J. Raupp. 2014. Managing Insects and Mites on Woody Plants: an IPM approach. Third Edition, revised. Tree Care Industry Assoc. Londonderry, NH. 175pp. Illus. and the Pest Predictive Calendar, also the Scale Crawler Emergence Period chart compiled by Stanton Gill, Suzanne Klick, and Sarah Kenney.

Complied by Miri Talabac, Horticulturalist & Coordinator, HGIC. 2022