PestMedium Severity

Fall Web Worm

Hyphantria cunea (Lepidoptera: Erebidae)

A native North American moth whose larvae create distinctive white silk webs on terminal branches. Has two distinct races (blackhead and redhead) that vary in appearance and habits. While capable of significant defoliation, damage is typically more cosmetic than life-threatening to trees.

Peak Season: Larvae active July through mid-September, adults emerge May-June
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Fall Web Worm nests showing characteristic terminal webbing

Identification & Symptoms

What to Look For

Large white silk webs enclosing terminal branches and leaves
Major defoliation of upper crown areas in August
Larvae visible inside webs, jerking when disturbed
Web enlargement as larvae include new leaves for feeding
Late-stage larvae may scatter beyond webs to feed on any green material
Multiple generations can cause extensive unsightly webbing

Potential Damage

Defoliation primarily cosmetic rather than life-threatening
Can cause major defoliation of upper crown in late summer
Multiple generations increase aesthetic damage
Stress may predispose trees to other problems in severe cases
Web construction covers and kills enclosed foliage

Lifecycle

Adults emerge May-June to lay egg clusters on undersides of terminal leaves. Larvae spin tents and feed July through mid-September. Pupae overwinter in debris, soil, or attached to tree trunks in dark brown cocoons made of silk and larval hair. 1-4 generations per year (4 common in Gulf States).

Professional Treatment Approach

1

Physical removal of webs while small

2

Systemic insecticide injection for severe infestations

3

Bacillus thuringiensis applications during early larval stages

4

Pruning and destroying infested terminal branches

5

High-pressure water spray to disrupt webs

Recommended Mauget Products

Imicide

Professional-grade treatment specifically effective against fall web worm.

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Dinocide

Professional-grade treatment specifically effective against fall web worm.

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