PestHigh Severity

Hemlock Woolly Adelgid

Adelges tsugae (Sternorrhyncha: Adelgidae)

A destructive invasive pest native to East Asia that feeds by sucking sap from hemlock and spruce trees. In eastern North America, it gravely threatens eastern hemlock and Carolina hemlock populations through its feeding damage and hypersensitive tree response.

Peak Season: Active year-round, peak activity spring through fall
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Hemlock Woolly Adelgid showing characteristic white woolly masses

Identification & Symptoms

What to Look For

White cottony masses of wax on undersides of twigs and branches
Needle discoloration progressing from yellow to brown
Premature needle drop starting with older needles
Branch dieback beginning in lower crown
Declining tree vigor and stunted growth
Tree mortality in 4-15 years if untreated
Restriction of water transport in affected trees

Potential Damage

Feeds on nutrients in xylem ray cells at needle base
Causes hypersensitive response restricting water transport
Removes essential tree nutrients through piercing-sucking mouthparts
Stress factors intensify effects leading to decline and death
Affects trees of all age classes
Can create characteristic round galls on spruce hosts

Lifecycle

Complex alternating host lifecycle with asexual generations on hemlock and sexual generation on spruce (where available). Two asexual generations per year on hemlock, with winged migrants (sexuparae) capable of flying to spruce hosts. Fundatrix overwinters near buds and begins feeding in spring.

Professional Treatment Approach

1

Systemic insecticide injection during active feeding periods

2

Horticultural oil applications to smother adelgids

3

Biological control with predatory beetles where established

4

Preventive treatments for high-value specimens

5

Regular monitoring of susceptible hemlock stands

Recommended Mauget Products

Imicide

Professional-grade treatment specifically effective against hemlock woolly adelgid.

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Dinocide

Professional-grade treatment specifically effective against hemlock woolly adelgid.

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