Saco · York County

Hemlock Woolly Adelgid Treatment in Saco, ME

Hemlock woolly adelgid is established in Saco. Tree Medics inspects and treats hemlocks across York County to keep them healthy.

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Inspecting a hemlock branch for woolly adelgid
CountyYork County
HWA in SacoEstablished
Check twigsTwice a year
One treatment can last4+ years

Hemlock woolly adelgid is a tiny, aphid-like insect from Asia that feeds on the sap of eastern hemlocks. Over several years, a heavy infestation can starve a hemlock of the stored energy it needs to grow, and the tree slowly declines. York County is entirely within Maine’s hemlock woolly adelgid quarantine.[1]

Hemlock woolly adelgid in Saco

As of December 2024, the Maine Forest Service lists hemlock woolly adelgid as established in Saco, and says it is widespread along the southern coast.[2]

Treatment options for hemlocks

Long-lastingImidaclopridFor hemlocks under three feet in diameter, one soil application can keep adelgid below damaging levels for more than four years.[3] It moves slowly, taking a year or more to reach the top of a large tree.[4]
Fast-actingDinotefuranMoves through the tree faster, which makes it useful for heavily infested hemlocks, but protects for only one to two years.[4]
Small treesOil and soapHorticultural oil and insecticidal soap can work on small trees, but need thorough coverage once or twice a year.[3]

How we treat hemlocks in Saco

Step 1InspectWe check the underside of branches for adelgid and judge how much healthy foliage the tree still has.
Step 2Choose the right treatmentHeavily infested trees may need fast-acting treatment first, while healthier trees can get long-lasting protection.
Step 3MonitorWe keep an eye on treated hemlocks so they can be retreated when needed.
Hemlocks respond best when treated early.

Systemic treatments rely on the tree to move them up into its branches. A hemlock with plenty of healthy foliage takes up treatment far better than one that is already in steep decline. Untreated infested hemlocks are likely to die within four to ten years.[4]

Why hemlocks matter

Eastern hemlocks are long-lived, shade-tolerant evergreens that provide year-round screening, shade streams and hold soil on slopes. Losing a mature hemlock changes a property, and replacing one takes decades.

Want the full picture? Read our complete guide to hemlock woolly adelgid treatment in Southern Maine.

Hemlocks and woods in Saco

Local landscapeSaco is a York County city with a 2020 Census population of 20,381 and a land area of about 38.6 square miles.[5]
Hemlock woolly adelgidBy July 2009 the Maine Forest Service had found hemlock woolly adelgid in Saco, one of seven southern Maine towns with known infestations at the time.[6]
Local landscapeThe Maine Natural Areas Program describes Saco Heath as the southernmost coalesced domed bog in Maine and one of only four state sites supporting the endangered Hessel’s hairstreak butterfly, whose larvae feed only on Atlantic white cedar.[7]

Hemlock Woolly Adelgid help near Saco

Tree Medics is based in Biddeford and works throughout Southern Maine. We also offer hemlock woolly adelgid services in nearby towns:

Biddeford, MEScarborough, MEKennebunkport, ME

See all tree care in Saco.

Sources

  1. Maine DACF: Hemlock woolly adelgid quarantine counties and towns
  2. Maine Forest Service: Hemlock woolly adelgid overview and distribution
  3. Maine Forest Service: Hemlock woolly adelgid fact sheet
  4. Michigan Invasive Species Program: Plan to treat trees for hemlock woolly adelgid (2026)
  5. U.S. Census Bureau: QuickFacts, Saco city, Maine (2020 Census)
  6. Bangor Daily News: Maine hemlocks to be surveyed for adelgids (2009)
  7. Maine Natural Areas Program: Saco Heath Focus Area of Statewide Ecological Significance
FAQ

Hemlock Woolly Adelgid in Saco: common questions

Is hemlock woolly adelgid in Saco?

Yes. As of December 2024, the Maine Forest Service lists hemlock woolly adelgid as established in Saco.

What does hemlock woolly adelgid look like?

Look for small white, cottony masses on the underside of young hemlock twigs at the base of the needles. Check twice a year, at the start and end of Daylight Saving Time.

How long does hemlock treatment last?

For hemlocks under three feet in diameter, one imidacloprid soil application can keep adelgid below damaging levels for more than four years. Dinotefuran works faster but lasts one to two years.

Can a hemlock with adelgid be saved?

Often, yes, especially when treatment starts while the tree still has plenty of healthy foliage. Untreated infested hemlocks are likely to die within four to ten years.

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Worried about a tree?

Many tree health problems can be managed when they are caught early. Reach out today for a professional evaluation.

(207) 303-7291 SaveMyTrees@TreeMedics.com

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