The hemlock woolly adelgid (/ əˈdɛl.dʒɪd /; Adelges tsugae
Hemlock woolly adelgid
Hemlock woolly adelgid, or HWA, is member of the Sternorrhyncha suborder of the order Hemiptera and native to East Asia. It feeds by sucking sap from hemlock and spruce trees. In its native range, HWA is not a serious pest because populations are managed by natural predators and parasitoid…
What is eating my hemlock trees?
Hemlock trees showing woolly adelgid damage. The hemlock woolly adelgid is a tiny, aphid-like insect that is ravaging hemlocks from Maine to Georgia. It attacks large native hemlock forests as well as hemlock landscape trees in your yard.
What bugs eat hemlock woolly adelgid?
Laricobius nigrinus is a small beetle that eats an even smaller bug – the hemlock woolly adelgid, or HWA. Since 2003, Laricobius has been used to help control HWA. But the beetle, which is native to western North America, is only active during the fall, winter and early spring. Recently, USDA Forest Service research entomologist…
How do you identify hemlock adelgid wool?
The adelgids feed at the base of the needles, where the needles attach to the woody portion of the shoot. It is often easier to see hemlock woolly adelgid wool on the undersides of shoots, but you can also find them on the upper side as well. Check hemlock shoots for the hemlock woolly adelgid’s white “wool” egg sac.
Where do you find adelgids in Hemlock?
The adelgids feed at the base of the needles, where the needles attach to the woody portion of the shoot. It is often easier to see hemlock woolly adelgid wool on the undersides of shoots, but you can also find them on the upper side as well.
Do birds eat hemlock woolly adelgid?
Another of the hemlock-associated species is the blue-headed vireo. As the hemlocks die, victims of the hemlock woolly adelgid, birds that depend on those trees leave, leading to a loss of biodiversity in the forest.
What is the host of hemlock woolly adelgid?
The hemlock woolly adelgid (Adelges tsugae) utilizes hemlock as its secondary host, where the asexual cycle occurs and spruce as its primary host, where the sexual cycle occurs. In North America the sexual cycle has not been previously recorded. Young twigs are the preferred feeding sites.
How does the hemlock woolly adelgid spread?
Hemlock woolly adelgids are spread by wind, birds, and mammals. Infested nursery stock can also be responsible for introducing this insect into a given area.
Is hemlock adelgid a parasite?
This tiny parasite spreads across the forest by hitch-hiking on birds. HWA use sucking mouthparts to pierce through the base of the hemlock needles into the parenchyma cells (nutrient transport cells). Large infestations can quickly deplete trees of their vital nutrients.
What kills woolly adelgid?
Homeowners and private landowners have two treatment options: 1) spray foliage with insecticidal soap or horticultural oil at the proper times during the HWA life cycle, or 2) use a systemic insecticide that moves with the tree sap and is consumed by the adelgids as they feed.
How often do hemlocks need to be treated?
once every one to two yearsHemlock trees will need to be protected from hemlock woolly adelgid in the future by treating them once every one to two years with products containing dinotefuran, or once every four to five years with products containing imidacloprid.
What is killing my hemlock tree?
Hemlock woolly adelgid (Adelges tsugae Annand), a tiny aphid-like insect native to Japan, is one of the most damaging invasive forest pests in eastern North America. Since it was discovered in 1951 in Virginia, this pest has been spreading across much of the range of eastern hemlock (Tsuga canadensis).
Is hemlock bug resistant?
Are there any hemlock species that are resistant to this pest? Yes. The mountain hemlock (Tsuga mertensiana) and the western hemlock (Tsuga heterophylla) are both native plants in this country and are highly resistant to HWA. However, when these plants are under previous stress, they can succumb to this pest.
What trees does hemlock woolly adelgid affect?
The hemlock woolly adelgid in eastern US originated from southern Honshu island, Japan and infestations have since spread widely to attack eastern hemlock, Tsuga canadensis, and Carolina hemlock, Tsuga caroliniana.
Do ladybugs eat woolly adelgid?
Ladybugs do eat the hemlock woolly adelgid, but there are two main reasons why they don't have any impact on controlling the HWA population. Ladybugs are just snacking on HWA.
How do you fertilize a hemlock tree?
Fertilizing - Feed young Hemlocks once a year in the fall. After they have been planted a year, sprinkle an all-purpose slow acting granular fertilizer on the soil under the tree out to 1 or 1½ feet beyond the tips of the branches (the drip line). Do not allow the fertilizer to touch the tree trunk.
What does woolly adelgid do?
The hemlock woolly adelgid sucks sap from hemlock needles, killing needles, shoots and branches. Infested hemlocks become less vigorous and may turn grayish-green. Left untreated, hemlock woolly adelgid can cause tree death in 4-10 years.
How long has the hemlock woolly adelgid been in the park?
The hemlock woolly adelgid has infested hemlocks on the Blue Ridge Parkway for about 10 years and in Shenandoah National Park since the late 1980s. In these areas as many as 80 percent of the hemlocks have died due ...
What is a woolly adelgid?
The hemlock woolly adelgid ( Adelges tsugae) is an aphid-like insect that covers itself with a white, waxy "wool" which acts as a protective coating for the insect. Adelgid infestations are easily recognizable by the appearance of tiny "cotton balls" at the base of hemlock needles. The "wool" is most conspicuous on the undersides ...
What is the name of the hemlock tree that has cotton balls?
Adelgid infestations are easily recognizable by the appearance of tiny “cotton balls” at the base of hemlock needles. Eastern hemlock trees are some of the largest and most common trees in the Great Smoky Mountains.
What is the best treatment for hemlocks in the park?
Hemlocks that are growing off trail in the park's forests or are too tall to be sprayed are treated with a systemic insecticide (imidacloprid) either by soil drenching or by injecting the insecticide directly into the trunk. Imidacloprid is the active ingredient found in tick and flea medication for dogs.
What is the wool on hemlock?
The "wool" is most conspicuous on the undersides of branches from fall through spring. The hemlock woolly adelgid feeds on the sap at the base of hemlock needles, disrupting nutrient flow and causing the needles to change from deep green to a grayish green, then fall off.
Why are hemlock trees important?
Hemlocks play an important role by providing deep shade along creeks, maintaining cool micro-climates critical to survival of trout and other cold water species. The impact of widespread loss of hemlock could trigger changes more significant as those that followed the demise of the American Chestnut in the 1930s and 40s.
What is the active ingredient in tick and flea medicine for dogs?
Imidacloprid is the active ingredient found in tick and flea medication for dogs. Soil drenching involves temporarily removing the duff-a layer of organic matter-from around the base of the tree then pouring a mixture of imidacloprid and water on the bare ground around the tree within a foot of the trunk.
How cold can adelgids survive?
Studies in northeastern states have shown that HWA mortality can exceed 90 percent if temperatures drop below -22° F. Winter mortality may be an important factor helping to slow HWA spread and population growth in areas of northern lower Michigan and the Upper Peninsula. It is important to remember, however, that temperatures in a forest can vary considerably, depending on factors such as exposure, aspect or height. The dense mass of white wax produced by the adelgids probably helps to protect them from cold temperatures to some degree. In addition, because all HWAs are female and two generations occur each year, if even a few adelgids survive a cold snap, the population can build up rapidly. There is also evidence that the ability to tolerate cold temperatures is a genetically linked trait that adelgids pass on to their offspring. Populations of HWA in northern latitudes in New England and New York, for example, appear to have become more cold-tolerant than HWA populations in southern states.
What is the wax on adelgids called?
This wax — called “ovisacs” — covers the adelgids, protecting the insects and their eggs from desiccation and natural enemies. The white ovisacs are most obvious from late fall to early summer, especially on the undersides of shoots. Hemlock woolly adelgid completes two generations each year.
How do adelgids reproduce?
In North America, HWA completes two life cycles per year on hemlock trees. Reproduction is asexual — that is, all adelgids are female. In spring, a generation of adelgids called “progrediens” hatch from eggs. The crawlers (first stage) can move about on the tree until they find places to settle. Crawlers can be blown by wind to other trees and can also be transported by birds or other animals that perch on or brush against an infested tree. Most of the progrediens will settle at the base of needles on the previous year’s shoots. Once they settle and insert their long stylets into the woody shoots to begin feeding, they will not move again. As the adelgids feed, they produce the strands of white wax from special glands on their bodies. The word “progrediens” comes from a Latin word meaning “to progress.” This generation of HWA does not require a long diapause period, and development “progresses” relatively quickly to the adult stage.
What do hemlock adelgids eat?
They feed at the bases of hemlock needles, where the needles attach to the woody shoots. As the adelgids feed, they secrete white, fluffy strands of wax from pores on their body.
How many generations does a Hemlock Woolly Adelgid have?
Hemlock woolly adelgid completes two generations each year.
What is the most unwanted tree in Michigan?
Hemlock woolly adelgid ( Adelges tsugae Annad) has been on Michigan’s “most unwanted” list for years. This invasive forest insect has killed hundreds of thousands of hemlocks ( Tsuga canadensis) in eastern states. It threatens more than 170 million hemlock trees in Michigan forests, and if not controlled, it will also kill hemlock trees in landscapes.
Why can't hemlock trees be protected?
Of course, the millions of hemlock trees in forests cannot be protected with systemic insecticides because of costs and environmental concerns. Efforts to identify, rear and introduce biological control agents to suppress HWA populations in forests have been underway for at least 20 years.
What is the name of the aphid that feeds on hemlock trees?
Hemlock woolly adelgid, which is related to aphids and scales, feeds on the hemlock's tissues and the build-up of large populations can result in the decline and death of hemlock trees. Hemlock woolly adelgid has been expanding its range in New Hampshire since it was initially detected in1999.
Where does the Hemlock Woolly Adelgid come from?
Hemlock Woolly Adelgid. Hemlock woolly adelgid (Adelges tsugae) is a small invasive insect native to Asia that is a threat to the health and sustainability of eastern hemlock (Tsuga canadensis) and Carolina hemlock (Tsuga caroliniana).
Is hemlock adelgid invasive?
Hemlock woolly adelgid is also a prohibited invasive insect in the state (Agr 3802.01)-it is not permissible to transport live hemlock woolly adelgid except for purposes of destruction. Hemlock woolly adelgid and other hemlock pests threaten the landscape and natural hemlocks of New Hampshire.
Can hemlocks be protected from drought?
The public should learn how to identify this pest and report it (NHBugs.org) where it is found. Landscape hemlocks should be protected from drought, and when infestations are suspected, they should be confirmed by a tree car professional who can offer assistance on managing tree health.
How long does it take for hemlock to go away after insecticide?
The hemlock woolly adelgid wool (egg sacs) will not disappear immediately after treatment, but will eventually weather away. Examine the new needles one or two years after applying the insecticide to determine if the treatment was effective.
How to report hemlock infestation?
It will be especially helpful to notify MDARD if the infestation is outside of the current infestation areas indicated on their HWA website .
How to report hemlock tree infestation in Michigan?
If it appears your hemlock tree is infested with hemlock woolly adelgid and you would like to confirm your identification, take photos, note the location of the tree and report it to the Michigan Department of Agriculture and Rural Development (MDARD) by emailing [email protected]. You can also call MDARD at 800-292-3939 to report a suspected hemlock woolly adelgid infestation. It will be especially helpful to notify MDARD if the infestation is outside of the current infestation areas indicated on their HWA website.
What does a hemlock tree look like?
Many people who check their hemlock trees may notice small, white spots that look a bit like hemlock woolly adelgid. Other insects, including the elongate hemlock scale, oak skeletonizer cocoons, caterpillar cocoons or spider egg sacs may be present on hemlock needles or shoots.
How to identify hemlock woolly adelgid?
The easiest way to identify hemlock woolly adelgid is to look at hemlock shoots for the white “wool” the adelgid produces while feeding. Each little white ball of wool, called an egg sac, is actually wax secreted by an adelgid. The adelgids feed at the base of the needles, where the needles attach to the woody portion of the shoot. It is often easier to see hemlock woolly adelgid wool on the undersides of shoots, but you can also find them on the upper side as well.
How to tell if a hemlock tree is a fir or spruce?
Before looking for hemlock woolly adelgid, make sure your tree is a hemlock and not a fir, pine or spruce tree. Hemlocks can be distinguished from pine and spruce by their short, flat needles. Hemlock needles are only about a half-inch long, which is much shorter than most pine needles. You can roll pine and spruce needles between your fingers, but not the flat hemlock needles. The underside of hemlock needles have pale white stripes, which will distinguish them from pines and spruces. However, the undersides of Douglas fir and balsam fir needles may also have pale white stripes, so you will need to look at the shape of the needles to distinguish hemlocks.
How long does it take for hemlock to die?
If the adelgid is not controlled, infested trees will decline and eventually die, usually within four to 10 years.
What to do if you have woolly adelgid?
If you’ve spotted a woolly adelgid infestation in your trees, there are options available for treatment. Unfortunately, the most effective options aren’t the most organic ones, so exercise caution when treating your trees. Begin by treating the trees that are the healthiest, the most integral to your landscape design, ...
What is the aphid on hemlock trees?
Hemlock trees showing woolly adelgid damage. The hemlock woo lly adelgid is a tiny, aphid-like insect that is ravaging hemlocks from Maine to Georgia . It attacks large native hemlock forests as well as hemlock landscape trees in your yard. The woolly adelgid is considered a serious threat to species of eastern hemlocks as well as ...
How to identify woolly adelgid?
It targets soft new growth, setting up camp right where the needles meet the stem. The hatching insects feed on the sap at the base of the needles, eventually causing those needles (and soon, the entire branch) to die.
What is the best treatment for woolly adelgid?
Soil treatment, or soil drenching, is considered the most effective method of treating the woolly adelgid in home landscapes. Follow these steps:
What to use on hemlocks?
If your hemlocks are small, you can use a foliar spray to spray the needles and stems with Imidacloprid.
Where did the hemlock adelgid come from?
It’s hard to pronounce, and sometimes it’s even harder to see. The hemlock woolly adelgid (HWA) is a fluid feeding insect that snuck into the United States from Asia, where it’s a harmless forest resident. It was first found in the western part of the U.S. back in the 1920s, but the woolly adelgid didn’t pose a threat there either. However, as the woolly adelgid made its way east, it soon became apparent that the tiny insect was a serious threat to eastern and Carolina hemlocks.
Where was the woolly adelgid first found?
It was first found in the western part of the U.S. back in the 1920s, but the woolly adelgid didn’t pose a threat there either. However, as the woolly adelgid made its way east, it soon became apparent that the tiny insect was a serious threat to eastern and Carolina hemlocks.
Ecology
Environment
- Over 800 acres of old-growth hemlock trees grow in the Smokies-more than in any other national park. Younger hemlock forests of 75-100 years in age cover an additional 90,000 acres of land in the park. Originally discovered here in 2002, adelgid infestations have now spread throughout the park's hemlock forests. In many areas infested trees have now died.
Distribution
- Since its arrival in the U.S. in the 1920s the hemlock woolly adelgid has rapidly colonized parts of New England and the Mid-Atlantic States, where it feeds on eastern hemlock. In the south, it also feeds on Carolina hemlock. The insect is easily dispersed by birds and wind but travels most rapidly as a hitchhiker on infested horticultural material...
Conservation
- The hemlock woolly adelgid has infested hemlocks on the Blue Ridge Parkway for about 10 years and in Shenandoah National Park since the late 1980s. In these areas as many as 80 percent of the hemlocks have died due to infestation.
Effects
- Hemlocks play an important role by providing deep shade along creeks, maintaining cool micro-climates critical to survival of trout and other cold water species. The impact of widespread loss of hemlock could trigger changes more significant as those that followed the demise of the American Chestnut in the 1930s and 40s.
Appearance
- The hemlock woolly adelgid (Adelges tsugae) is an aphid-like insect that covers itself with a white, waxy \"wool\" which acts as a protective coating for the insect. Adelgid infestations are easily recognizable by the appearance of tiny \"cotton balls\" at the base of hemlock needles. The \"wool\" is most conspicuous on the undersides of branches from fall through spring.
Biology
- The hemlock woolly adelgid feeds on the sap at the base of hemlock needles, disrupting nutrient flow and causing the needles to change from deep green to a grayish green, then fall off. Without needles the tree starves to death, usually within three to five years of the initial attack. Infestations often start in large, mature hemlocks, but the insect also attacks and kills younger trees as well.
Treatment
- Three different types of treatments are used to kill adelgids on hemlock trees: Foliar Treatments Hemlocks in developed areas and sites accessible by road are treated with insecticidal soap or horticultural oils. Sprayed from truck-mounted spray units, these sprays smother and dry-out the adelgids on contact. The equipment can spray up to 80 feet into the canopy of large roadside tre…
Future
- You Can Help Although the adelgid will forever alter hemlock forests of the Smokies, with continued funding, dedicated staff, and committed partners, there will still be a healthy patchwork of hemlock in the park and future visitors will still be able to marvel at the \"redwood of the east.\"
Management
- Efforts to control hemlock woolly adelgids are being funded through the Save the Hemlocks initiative of the Friends of Great Smoky Mountains National Park, a nonprofit organization. For additional information, call (865) 932-4794.
Community
- Learn More About the Adelgid For additional information, watch a brief video about the hemlock woolly adelgid, visit here or call (865) 436-1730.