Free Republic
Browse · Search
Topics · Post Article

Skip to comments.

Insects Endangering Hemlock Stands
Associated Press ^ | Mon Jul 28,10:43 AM ET | DAN LEWERENZ

Posted on 07/28/2003 2:02:01 PM PDT by anymouse

BALD EAGLE STATE FOREST, Pa. - At first glance, the forest around Sand Spring Run looks just as it should, with a lush understory of grasses and ferns shaded by tall maple, oak and hemlock.

But a closer look shows that the hemlock trees — a keystone species along streams like this — are under attack from at least two insects with the potential to devastate hemlock stands throughout the Northeast.

Usually dark green, the hemlock's needles have faded to a pale, almost yellow color indicative of an infestation of elongate hemlock scale insects. The cottony, white spots indicate the tree also is infested with hemlock woolly adelgid. Together, these insects are teaming up on hemlocks from Virginia to southern New England and west to Ohio.

"When you combine elongate hemlock scale and hemlock woolly adelgid, that really is a one-two punch," said Richard Cowles, associate entomologist at the Connecticut Agricultural Experiment Station.

And their bite has gotten worse in recent years, when much of the Northeast suffered under drought conditions. Both insects survive by piercing hemlock needles and sucking them dry — the adelgid feeds directly on the tree's vascular system, while the elongate scale (there are multiple hemlock scale species) drains fluid from the tree's cells.

"The drought stress of previous years, in combination with these insects that have piercing, sucking mouth parts, have really exacerbated the whole effect and have led to an even more quick decline of hemlock in the forest, as well as in the landscape," said Greg Hoover, a Penn State University Extension entomologist.

Although it once served as a source of tannic acid for tanning leather and hides, the tree now is valued more for its aesthetic and environmental value.

"Our 167 state parks, virtually all of them were placed in hemlock stands, because of the streams and the cool shade, the idyllic forest setting," said Mike Blumenthal, forest health supervisor for the Pennsylvania Bureau of Forestry. "It would have a tremendous impact on recreation if we were to lose hemlocks.

"Hemlocks also are extremely important in stabilizing the soil around streams, in filtering the water that goes into those headwater streams. They're very, very important in preserving water quality," Blumenthal said.

Scientists have developed several methods of fighting the woolly adelgid, including both topical and systemic insecticides and finding beetle species that will eat the adelgid.

But elongate hemlock scale has proven to be more of a problem. Because hemlocks grow in environmentally sensitive areas, spraying topical pesticides is impractical, Hoover said; and even where they can be sprayed, the insect coats itself in a waxy, protective substance.

Systemic insecticides don't seem to work either, Hoover said, and can even ward off or poison species that might prey on the elongate hemlock scale.

But researchers in New Jersey have identified a beetle, Cybocephalus nipponicus, that might be used in fighting elongate hemlock scale. Pennsylvania officials have released 2,000 of the beetles in a scale-infected forest in Lycoming County, and hope to have more by the end of the summer.

"Fairly recently, and quite by accident, the New Jersey Department of Agriculture was rearing an exotic predatory beetle from Korea that eats the scale pest of a horticultural shrubbery," Blumenthal said. "They quite accidentally found that this beetle moved over from infected Euonymus scale to elongate hemlock scale."

Cowles said there's also hope in a fungus found in southwestern Connecticut and eastern New York that seems to be infecting the insect without affecting other species. Scientists are trying to identify the fungus and determine whether it can be used against elongate hemlock scale elsewhere.

"This fungus, at this point, does not seem to be one that can be grown on petri dishes. ... It has to be in the host, so we haven't even been able to identify what the fungus is," Cowles said.

TOPICS: Culture/Society; Government; News/Current Events; Technical; US: Connecticut; US: New Jersey; US: New York; US: Pennsylvania
KEYWORDS: nature; pesticide; poison; science
Apparently nature is attacking nature.

Tough bug to feast on Hemlock, a source of a deadly poison.

Although tried natural preditory bugs and funguses, and man-made insecticides (not all known insecticides like DDT) have not worked, one has to wonder what would happen to the Hemlock population without man's intervention to save it?

1 posted on 07/28/2003 2:02:01 PM PDT by anymouse
[ Post Reply | Private Reply | View Replies]

Comment #2 Removed by Moderator

To: anymouse
The poison comes from the hemlock plant.

The hemlock tree, is completely unrelated to the plant, and is not poisonous.

3 posted on 07/28/2003 2:05:34 PM PDT by B Knotts
[ Post Reply | Private Reply | To 1 | View Replies]

To: B Knotts
I think the Indians used the Hemlocks as a source of Vitamin C, and taught the colonials to do the same. Our two sixty foot trees in our back yard will have to be removed; they are being deccimated by the diseases as have all the other Hemlocks in our neighborhood, a neighborhood with many beautiful old growth trees on the Hudson Highlands. V's wife.
4 posted on 07/28/2003 2:13:39 PM PDT by ventana
[ Post Reply | Private Reply | To 3 | View Replies]

To: B Knotts
Hemlocks might not be poisonous per se, buy they do a good job of killing off other vegetation. The needles are so acidic very few things can survive in the soil after a few years.

The Hemlocks in Shenandoah are almost all dead because these buggers.
5 posted on 07/28/2003 2:19:16 PM PDT by jae471
[ Post Reply | Private Reply | To 3 | View Replies]

To: jae471
Maybe you have to think "survival of the fittest" and see what steps in to replace them.

We had one stand of American Chestnut trees left. The hot "tree man" in our area medicated the trees to try to save them. They ALL died much sooner than they would have naturally and he said the species might have "hardened up" and survived if he had not medicated them.

6 posted on 07/28/2003 2:34:25 PM PDT by Sacajaweau (God Bless Our Troops!!)
[ Post Reply | Private Reply | To 5 | View Replies]

To: ventana
You're quite right. Many of the surveyors wrote that they used the bark with great success against the fever and ague (sp??). I believe it is mentioned in the Lewis and Clark diaries also.
7 posted on 07/28/2003 2:37:43 PM PDT by Sacajaweau (God Bless Our Troops!!)
[ Post Reply | Private Reply | To 4 | View Replies]

To: jae471
The Hemlocks in Shenandoah -- sounds like a quaint little bed-and-breakfast.....
8 posted on 07/28/2003 2:43:36 PM PDT by tracer (/b>)
[ Post Reply | Private Reply | To 5 | View Replies]

To: anymouse
Here in Connecticut it's sad to see what's happening due to this blight. The hemlocks, which like to grow on the banks of rivers & streams, are dying, which is causing the water's banks to erode at an alarming rate.
I spoke with a forest ranger recently, at a State Park, and he was very pessimistic as to what could be done. He basically conceded that the hemlock forests will be gone.And here in CT, we have a lot of hemlock forests. But, I suppose, the deciduous trees that replace them, will be pretty in the Fall.
9 posted on 07/28/2003 2:45:20 PM PDT by PaulJ
[ Post Reply | Private Reply | To 1 | View Replies]

To: PaulJ
Wow! I'm here in southwestern Mass, and I haven't noticed any decline in Hemlocks - I'll have to take more notice on my next hike, and see if I see signs... :-(
10 posted on 07/28/2003 3:30:41 PM PDT by StatesEnemy
[ Post Reply | Private Reply | To 9 | View Replies]

To: All
And the kicker.... they are an 'All Female' species:

The soft-bodied insects, only 1 millimeter long, overwinter in the trees as wingless adult females, which lay eggs in April. Newly hatched nymphs, or "crawlers," migrate to the young branches and settle at the base of the needles to feed. In June, new adult females secrete the white, waxy covering that looks like tiny tufts of cotton or wool in which they lay more eggs, and for which the insect was named.

A winged form of the insect develops from the first generation, and migrates to other hemlock or even spruce. That, along with wind and birds, plus the biological quirk that all adelgids are female and therefore egg-layers, accounts for the insect's rapid spread.

Tiny woolly adelgids threaten state's mighty hemlocks

11 posted on 07/28/2003 3:37:55 PM PDT by StatesEnemy
[ Post Reply | Private Reply | To 10 | View Replies]

To: StatesEnemy
Try October Mountain. The bottom half to two thirds of the hemlocks are gone.
12 posted on 07/28/2003 3:39:40 PM PDT by PaulJ
[ Post Reply | Private Reply | To 10 | View Replies]

To: PaulJ
The worst thing about evolution is the bitching when it works.
13 posted on 07/28/2003 3:54:17 PM PDT by Old Professer
[ Post Reply | Private Reply | To 12 | View Replies]

To: B Knotts
Never mind. :]
14 posted on 07/28/2003 4:03:04 PM PDT by anymouse
[ Post Reply | Private Reply | To 3 | View Replies]

To: anymouse

University of Pennsylvania..POISON HEMLOCK - Conium maculatum (More Pictures Here)

This site has some information about the Hemlock Tree and Plant, including medicinal recipes.

Medicinal Herbs Online

I love Hemlocks. I still remember them on the rivers I fished as a kid.


15 posted on 07/28/2003 4:22:36 PM PDT by longjack
[ Post Reply | Private Reply | To 1 | View Replies]

To: Old Professer
Who's bitching?
16 posted on 07/28/2003 4:57:31 PM PDT by PaulJ
[ Post Reply | Private Reply | To 13 | View Replies]

To: anymouse
Natural populations of species ebb and flow in nature. Sometimes when stressed (like happened with Gypsy Moth and Oaks) many perish but some survive, with better strength for the future. In other cases (like glacial ages) the stress is too great and the species die out.

I expect that we will lose a lot of our Hemlocks, but those that survive will drop seeds and new forests of stronger, more resistent hemlocks will spring up. Will it be the same again in our lifetimes? Probably not, but the cycle of things isn't dependent on any one of us being here to see it...
17 posted on 07/31/2003 4:42:51 PM PDT by Kay Ludlow
[ Post Reply | Private Reply | To 1 | View Replies]

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.

Free Republic
Browse · Search
Topics · Post Article

FreeRepublic, LLC, PO BOX 9771, FRESNO, CA 93794 is powered by software copyright 2000-2008 John Robinson