When Adelgids Attack

Hemlock woolly adelgid

A hemlock woolly adelgid is about the size and color of a period at the end of the sentence. They would be virtually impossible to spot if it weren't for the fact that they encase themselves in waxy woolly balls.

What Does It Do to my Trees?

Adelgids are tiny insects that feed on the starch reserves of conifers. They're related to aphids.

Hemlock woolly adelgids produce two generations per year. The mature female lays eggs under her body, protected by a cottony mass of filaments. When an egg hatches, a tiny, mite-like, reddish-brown insect emerges.

Once the young adelgid finds a good spot to feed, it inserts a fine mouthpart, three times the length of its own body, deep into plant tissues, and stays there.

Adelgids don't directly eat sap; instead, they feed on starch reserves that the tree needs for growth and survival.

Once trees are infested with hemlock woolly adelgids, they often die within three or four years, but some hang on with just a bit of life at the very top of the tree.

Signs of Infection

The adelgids extrude numerous wavy filaments, which curl around to make what looks like a tiny cotton ball on a twig. The filaments are easiest to see in late winter.

Infested trees start having fewer new shoots, followed by needle loss. The tree often turns a grayish color and branches die back.

Check your woods for the insect. Focus on streams and areas of heavy wildlife traffic. From late winter to early spring, check the underside of the leaves for waxy white "cotton balls."

I've Got Hemlock Woolly Adelgids. Now What?

When you've determined your hemlocks are being attacked by hemlock woolly adelgid, you have multiple options

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