JULY 7 EDITION OF "ASK THE ARBORIST"

Today we are looking up close at the Hemlock Wooly Adelgid (Adelges tsugae).  According to literature cited from “The U.S. Forest Service” Wooly Adelgid is a small aphid like sucking insect native to Asia and presently threatens the sustainability and health of Eastern Hemlock.  Hemlock Wooly Adelgid was first reported in our country sometime in 1951 near Richmond Virginia.  Since 2005 Hemlock Wooly Adelgid has been reported from Nova Scotia to Northern Alabama. All varieties of Hemlocks can be attacked, but only Eastern and Carolina Hemlock are vulnerable when attacked.  Eastern and Carolina Hemlocks attacked by Hemlock Wooly Adelgid if left unchecked can die within 3 - 10 years by sucking dry the valuable nutrients the tree requires for survival.  Hemlock Woolly Adelgid as mentioned earlier are sucking insects that feed like a parasite off the host trees needles.    

The life cycle of Hemlock Woolly Adelgid is rather remarkable.  The insect is parthenogenetic meaning all individuals are females and reproducing occurs via asexual reproduction.  Hemlock Woolly Adelgid matures through six stages egg, four nymphal stages and then the adult.  There are usually two generations of Hemlock Wooly Adelgid per year.  Hemlock Woolly Adelgid feeding activity is unusual from most insects, in that it enters a dormancy period during the hot months of summer and then returns to feeding in the cooler weather of October and then continues to feed throughout the winter months.

Hemlock Wooly Adelgid is quite small, less than 1.5 mm and generally displays a color of dark reddish brown to purplish black.  As it matures and begins the egg laying process, the adult begins to produce wool like wax covering to protect the eggs from predators and help prevent the insect from drying out.

There are effective chemical treatments using low toxic horticulture oil to suffocate the insect covering the entire tree from March - April before the buds fully open.  Since we are dealing with a two generation insect and one that feeds during cooler seasons additional treatment in the fall would also be helpful for heavily infested Hemlocks.

Always remember proper diagnosis is imperative prior to any chemical treatment program.  Large Hemlocks will require high pressure equipment that only a professional may have readily available.

Contact your Yacko and Sons Tree Service Staff Forester to help diagnose any insect or disease concerns on your trees.  AND REMEMBER FORESTER JEFF IS ALWAYS AVAILABLE TO GIVE YOUR TREES A FREE LOOK-UP FROM THE TRUNK-UP!  jeff@yackoandsons.com or 203-733-9219