Attack of the Adelgids

The Eastern White Pine, Pinus Strobus, is a fast-growing native used for plantation plantings, screens (where there isn’t too much wind), specimen trees and hedges. Its needles are long, slender and soft, and they eventually cover the ground, making a woodland carpet.

The trunks are stately and the branches whorl around it. A mature tree has dark brown-ridged bark, which adds to the appeal of the tree. It is a handsome species, elegant and ornamental in shape, but it also serves as a valuable timber tree.

White Pines are one of the fastest-growing landscape pines, reaching 50-75 feet tall in about 25-40 years. Some consider them an invasive species, albeit a native one. At my house, they have proven to be not quite as tenacious. I am forever weeding out walnut and maple seedlings from my garden but I have never seen a self-sowed White Pine seedling. Reportedly, White Pine re-seeds itself so quickly, epescially in abandoned fields, that I remember my grandfather calling it “old field pine.”

At my house, we chose Eastern White Pine to fill in and add shade to what was originally pasture land. We planted 1,000 small saplings around the perimeter of the property for privacy when we first built our house. We prefer not to see our neighbors (and our neighbors feels the same way, though not from lack of friendliness. It’s rather the hermit mentality we rural dwellers often have). I remember the saplings at knee-height, and now I walk under them in a magical forest that borders my dirt driveway and opens up to the “glen” that encompasses my house.

In the 21 years of residence at South Turkey Creek, the White Pines have been the glory of the garden, creating a park-like atmosphere and giving me lots of pine needles for mulch. We thinned a few out in the early days, but now they are well established and easily reach 50 feet high. Our only real battle with them is Oriental Bittersweet, which has to be cut out of our trees each year.

This year, when everything else in our garden was growing heartily (we finally had some rain), the White Pines started to look, well, white. The trunk of each tree looks like Tom Sawyer conned some of friends into whitewashing them instead of Aunt Poly’s‘ fence. One side of then driveway glows in the dark from the white, cottony mass of the bark of each tree.

After dong some research, I discovered that the whitewashing was actually the work of the Pine Bark Adelgid–yes, similar to that same adelgid that attacks the hemlock but this one sticks to pines. It attacks Scotch Pines, Jack Pines, Ponderosa pines and Pitch pines, but mostly focuses on White Pines.

It turns out it isn’t going to kill my White Pines, although if the adelgids had attacked when they were knee-high to me, that would have been a problem. For mature trees the problem is primarily aesthetic.

This “whitewashing” is actually a white, wooly mass that’s created by the female to help hide her eggs; she lays about 24 in each cottony secretion. That means my trees had literally millions of adegid eggs on them, since each wolly mass is very small.

The hatchlings, called crawlers, have legs and can move about. A very few of them have wings, and these are primarily the females. The crawlers transform into another stage, called nymphs, and these settle in to feed and develop, which they do rapidly. Soon, they are mature and have 24 or so eggs beneath them, and so it goes. In one season there are easily five generations. In theory, one over-wintering mom could have about 8 million offspring by autumn.

This is a sobering thought, and one that has me wanting to rush out and buy natural predators, which come in the form of lady bettle larvae, several flies and the tooth-necked beetle. The tooth-necked bettle can exist solely on a diet of adelgids and is gaining some popularity in its abilty to control them naturally.

Adelgids are tiny, sap-sucking insects that are closely related to aphids, and they are often mistaken for them. The insects are about 1/32nd of an inch long, but their mouth parts, called stylets, are 1/16 of an inch long. The mouth parts are used to penetrate the bark into the phloem, a laywer of tissue inside the bark that transports food from the leaves to the roots. With this many adelgids sucking away on my trees, it seems impossible that damage can’t be done, but so far, there isn’t any, just as promised. The Pine Bark Adelgid is evidently one of the few gardening problems that will solve itself. It is short-lived and the adelgids move one.

That is my kind of gardening problem. Instead of fretting, I can actually marvel at the scene. Just think–something as small as 1/32nd of an inch finds a way to have it’s place in the world. Surely, that means there is room for me too.