Mimosa Webworm on Honeylocust Trees

Watch for this type of damage on Honeylocust trees during the summer months


The first thing you will notice are clusters of brown leaves near the branch tips of Honeylocusts (Gleditsia triacanthos).

The first generation lays eggs that hatch in mid-June. A second generation appears in early August.

These photos were taken in Pennsylvania in mid-September, after leaf damage had become extensive from both generations.

Mimosa Webworm on a thornless Honey Locust

Brown leaves appear near the branch tips in late summer. Severe infestations will completely defoliate a tree.


Mimosa Webworm caterpillars have 5 white stripes

Larvae overwinter in cocoons in leaf litter or under the bark of the tree. This means it's extra important to clean-up fall leaves around the tree and dispose of them elsewhere.

Mimosa Webworm leaf damage

Mimosa Webworm larvae spun webs around these Honeylocust leaves. The " to 1" long caterpillars may be brown or gray, and have 5 white stripes running the length of the caterpillar.

 

Solutions for Webworms

Plant resistant varieties of honeylocust like 'Shademaster', 'Skyline' and 'Moraine.'  Avoid 'Sunburst' honeylocust since it is very susceptible to Mimosa Webworm. Clean-up and dispose of fall leaves from your Honeylocust trees to help prevent overwintering of webworm cocoons.

If necessary, Bt ('DiPel' biological insecticide - bacillus thuringiensis) or chemical controls should be applied in late June or August. Always read the pesticide label and follow directions. Applications earlier in the year will be more effective since extensive webbing can prevent spray products from reaching the intended target. Repeat applications may be necessary.

MORE

Mimosa trees

Leaf mulch

Plum trees and scale insects

     


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