Mimosa Webworm Fact Sheet

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The Mimosa Webworm, Homadaula anisocentra (Meyric) was introduced from China to the U.S. in the 1940’s. Its larvae spin unsightly gray webs around foliage and feed on it. If undetected the larvae may completely defoliate the host plant.

Plants Attacked

The Mimosa Webworm attacks the leaves of both Mimosa (Albizia julibrissin) and honeylocust (Gleditsia triacanthos).

Insect Identification

Mature mimosa webworm larvae

Initially, the eggs are tiny, oval and pearly white, but turn pink when close to hatching. The larvae vary from gray to brown with five white stripes. The pupae are yellowish-brown and are located in silken cocoons. The adult, rarely seen, is a silver-gray moth with wings that are covered with black dots.

 

 

 

Life History

Winter	The larvae over-winter as pupae encased in cocoons. They are found under bark on the trunk of the host or in leaf litter under the tree.
Spring	The first generation moth lays gray eggs on the leaves of the host. After hatching in early to mid-June, the larvae spin webs around several leaves and feed on the lower surface of the leaflets.
Summer	When the larvae pupate in late July through mid-August, a second generation of moths appears. This second generation over-winters.

Feeding injury with webbed foliage on honeylocust	Dead leaves held together with webbing from the first generation mimosa webworm on honeylocust

Damage Symptoms

The larvae stage causes damage to the host plant by skeletonizing the leaves within the webs that they spin. Damage is most noticeable when the second generation larvae are at the peak of their activity in August. The webs of the mimosa webworm can encase whole trees making it difficult to assess the full extent of the damage.

Cocoon in a bark crevice on a honeylocust tree	Late summer damage to honeylocust

Management Options

Biological	There are many insects and birds that feed on the larvae.
Cultural	Prevention is the most effective way to control mimosa webworm. Species of honeylocust (Gleditsia triacanthos) reported to be less susceptible are ‘Moraine’, ‘Shademaster’ and ‘Imperial’. Gleditsia triacanthos ‘Sunburst’ is very vulnerable. Clearing away leaf debris around the host tree will decrease chances of infestation.
Chemical	Young larvae should be targeted with insecticide just after eggs hatch in mid-late June and in August Control Measures for Mimosa Webworm

Download Printable Fact Sheet

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Authored by:
Katherine Mazzey, Penn State Extension Program Assistant
Jessica Scott, Penn State Extension Program Assistant
Michael Masiuk, Extension Agent, Penn State University – Allegheny County

Sources
Day, E. (1996). Mimosa Webworm. Virginia Polytechnic Institute & State University. Virginia Cooperative Extension. http://www.ext.vt.edu/departments/entomology/factsheets/mimoworm.html

Gibb, T. J., Sadof, C. S. (2002). Momosa Webworm. Purdue University Cooperative Extension Service. http://www.ces.purdue.edu.

Hoover, G.A. (2000). Woody Ornamental Insect, Mite, and Disease Management. Penn State College of Agricultural Sciences. pp.39. http://woodypestguide.cas.psu.edu

Hoover, G.A. & Knupp, B. (2001). Mimosa Webworm. Department of Entomology. Penn State.
www.ento.psu.edu/extension/factsheets/mimosa_webworm.htm

Johnson, W.T. & Lyon, H.H. (1976). Insects That Feed On Trees And
Shrubs, pp.180. Comstock Publishing Associates. Cornell University Press.