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Insects
Redbay Ambrosia Beetle | Ips Engraver Beetle | Emerald Ash Borer | Gypsy Moth | Sirex Woodwasp
Description: Adult beetles are dark red-brown to almost black and 1/8 inch to 1/5 inch (3 to 5 mm) long. They are distinguished from other bark beetles by their scooped-out posterior with 4 to 6 spines on each side. Larvae have white bodies with orange-brown heads and are legless. Pupae are waxy-white and similar to adults in size. The female constructs an egg gallery and lays her eggs beneath the bark of attacked trees. The larvae make individual feeding galleries in the inner bark and pupate at the end of their galleries. New adults emerge after 21 to 40 days during the summer or after several months during the winter.
Damage: Ips engraver beetles kill more pine timber in the South than any other forest insect, with the exception of the southern pine beetle. Ips beetles usually attack injured, dying, or recently felled trees and fresh logging debris. Infestations are particularly common in trees weakened by drought or lightning strikes.The first signs of attack are reddish-brown boring dust in bark crevices or reddish-brown pitch tubes about the size of a dime on bark surfaces. If the bark is removed, there are Y- or H-shaped egg galleries with short larval galleries extending perpendicular to them. Egg galleries will usually be free of
boring dust. The foliage of Ips-killed pines will eventually turn yellow, and then red about the time the beetles complete development under the bark. Often only the top portion of the crown is killed, leaving lower branches green. Blue-stain fungi, introduced when the beetles attack the tree, is visible in the sapwood and hasten the death of the trees.
Control: The best control is prompt removal and utilization of actively infested trees, making sure that the bark and slabs are destroyed. Insect parasites and predators, woodpeckers, and weather provide natural controls. Chemical control is seldom warranted under forest conditions, but may be used to protect pines in urban or high value areas. Preventive control practices include minimizing logging damage to residual stands and quick removal of felled trees.
Redbay Ambrosia Beetle back to top
Description: Xyleborus glabratus adults are small, 2 mm long, slender, cylindrical, and brown-black in color. It is very similar to other members of the genus but the combination of its coloration, glabrous elytra, and abrupt declivity distinguishes it from other species (Mayfield and Thomas 2006). The larvae are white, c-shaped, legless grubs with an amber colored head capsule (Rabaglia 2005). A specialist should be consulted for positive identification of adults and larvae due to their similarity to other species. Very little is known about the life cycle and biology of Xyleborus glabratus. Adult females construct galleries in the sapwood and inoculate the galleries with a fungus (Ophiostoma sp., vascular wilt pathogen). The adults and larvae feed on fungi and not on the wood of the damaged host plant. Females are believed to be able to fly 2-3 km in search of a host. Males are dwarfed, haploid, and flightless and are rarely seen.
Hosts: In the US, Xyleborus glabratus has been associated with redbay and sassafras. The Ophiostoma fungus associated with Xyleborus glabratus has also been recovered from pond spice, indicating that this plant may also be a host. All plants are members of the family Lauraceae and are important to wildlife as browse and fruit plants. Redbay also serves as host to larvae of the Palamedes swallowtail (Papilio palamedes (Drury)), which feeds primarily on species of Persea.
Damage: The principal damage is tree wilt caused by colonization of the xylem cells by the Ophiostoma fungus. Attacked trees exhibit wilted foliage with reddish or purplish discoloration within a section of the crown or throughout the entire crown. The foliage eventually turns brown and tends to remain on the branches. Like other ambrosia beetles, small strings of sawdust (ejected wood fiber) may be present at the point of attack. The fungal infection is evidenced by stained sapwood visible upon removal of bark or in cross sections of the stem.
Control: No tested or proven treatments for the managing Xyleborus glabratus and its associated fungus. Like other exotic species, Xyleborus glabratus will continue to naturally expand its range. In order to reduce its spread, no wood or chips from infested trees should be transported out of the local area
Emerald Ash Borer back to top
Description:
The adult beetle is dark metallic green, bullet-shaped and about 8.5 millimetres (0.33 in) long and 1.6 mm (1⁄16 in) wide. The body is narrow and elongated, and the head is flat with black eyes. The larvae are approximately 1 mm (1⁄25 in) diameter, 26 to 32 millimetres (1.0 to 1.3 in) long, and are a creamy white color. The eggs turn to a yellow brown color prior to hatching. Adults lay eggs in crevasses in the bark. Larvae burrow into the bark after hatching and consume the cambium and phloem, effectively girdling the tree and causing death within two years. The average emerging season for the emerald ash borer is early spring to late summer. Females lay around 75 eggs, but up to 300 from early May to mid-July. The borer's life cycle is estimated to be one year in southern Michigan but may be up to two years in colder regions.
Life Cycle
The adult emerald ash borer emerges in May–July and the female lays numerous eggs in bark crevaces and between layers of bark. The eggs hatch in 7–10 days and larvae bore into the tree where they chew the inner bark and phloem creating winding galleries as they feed. This cuts off the flow of the water and nutrients in the tree, causing dieback and death
Hosts: Emerald ash borer (EAB) is native to Asia. It is known to be established in Michigan, Ontario, Ohio, Indiana, Illinois, and Maryland. EAB probably arrived in the United States on solid wood packing material from Asia. Hosts include all ash species; however, green ash, white ash, and black ash are more susceptible than Asian varieties
Damage: Vertical splits in the bark are created by the tree forming callus tissue in response to larval feeding. The damage by the larvae causes general yellowing and thinning of the foliage followed by crown dieback and the eventual death of the tree. Basal sprouting and the presence of woodpeckers may indicate wood-boring beetle activity. After 1 to 2 years of infestation, the bark often falls off in pieces from damaged trees, exposing the insect galleries.
Control: Recent research has shown that several chemical and biological agents are providing promising results in controlling the spread the EAB. The USDA APHIS in Michigan is testing the effects of three parasitoids (Tetrastichus planipennisi, Oobius agrili, and Spathius agili) to consume the EAB at various stages of its development. The Canadian Forest Service has been injecting a naturally-produced compound from the Neem seed which appears to be effective in inhibiting EAB larval development and preventing adult emergence. A third compound, emamectin benzoate (marketed under the name of Tree-age), has received emergency licensing in several states as a chemical to be injected into Fraxinus species to kill EAB larvae and adults.
Visit website for more information on control: http://www.emeraldashborer.info/
Gypsy Moth back to top
Description: The gypsy moth, which came from France, is considered one of the most important pests of red and white oaks in the Northeast. It has spread southward into Virginia and is continuing to move south. Older larvae are brownish-gray, with tufts of hair on each segment and a double row of five pairs of blue spots, followed by six pairs of red spots, on the back. Mature larvae are from 1 1/2 to 2 1/2 inches (40 to 60 mm) long. Adult male moths are dark brown, with wavy dark bands across the forewings. Females are white and cannot fly.
Hosts: Gypsy moth is known to feed on over 300 trees and shrubs. Favored hosts include oak, apple, alder, basswood, birch, poplar, sweet gum, willow, and hawthorn. Less favored host species include hickory, maple, cherry, cottonwood, elm, black gum, larch, sassafras, and hornbeam. Some mortality even occurs in white pine. Many other plants may be fed upon.
Damage: It causes widespread defoliation, resulting in reduced growth, loss of vigor, mortality, and reduces aesthetic, recreational, and wildlife values. Gypsy moth larvae can be a serious nuisance in urban and recreation areas.
Control: An effective way to dispose of gypsy moth life stages is to remove them by hand. Scrape egg masses from their locations with a putty knife, stiff brush, or similar handtool. Dispose of egg masses and other life stages in a container of hot water, household bleach, ammonia, or kerosene. Gypsy moth hairs, found attached to all life stages, can cause people who are allergic to them to have skin rashes or respiratory reactions. If necessary, wear gloves, protective clothing, and a dust mask. Natural controls, including introduced insect parasites and predators, virus diseases, and adverse weather conditions, help control the gypsy moth. Chemical and microbial insecticides have been used, primarily in urban and recreation areas, to prevent defoliation and the nuisance effects of the pest.
Sirex Woodwasp back to top
Description: Woodwasps (or horntails) are large, robust insects, usually 1.0 to 1.5 inches long . Adults have a spear-shaped plate (cornus) at the tail end; in addition females have a long ovipositor under this plate. Larvae are creamy white, legless, and have a distinctive dark spine at the rear of the abdomen . More than a dozen species of native horntails occur in North America. Key characteristics of the sirex woodwasp include: body dark metallic blue or black; abdomen of males black at base and tail end, with middle segments orange; legs reddish-yellow; feet (tarsi) black; males with black hind legs; antennae entirely black.
Transport: Sirex woodwasp has been the most common species of exotic woodwasp detected at United States ports-of-entry associated with solid wood packing materials. Recent detections of sirex woodwasp outside of port areas in the United States have raised concerns because this insect has the potential to cause significant mortality of pines. Awareness of the symptoms and signs of a sirex woodwasp infestation increases the chance of early detection, and thus, the rapid response needed to contain and manage this exotic forest pest.
Damage: Sirex woodwasp can attack living pines, while native woodwasps attack only dead and dying trees. At low populations, sirex woodwasp selects suppressed, stressed, and injured trees for egg laying. Foliage of infested trees initially wilts , and then changes color from dark green to light green, to yellow, and finally to red , during the 3-6 months following attack. Infested trees may have resin beads or dribbles at the egg laying sites, which are more common at the mid-bole level. Larval galleries are tightly packed with very fine sawdust. As adults emerge, they chew round exit holes that vary from 1/8 to 3/8 inch in diameter.
Control: Sirex woodwasp has been successfully managed using biological control agents. The key agent is a parasitic nematode, Deladenus siricidicola, which infects sirex woodwasp larvae, and ultimately sterilizes the adult females. These infected females emerge and lay infertile eggs that are filled with nematodes, which sustain and spread the nematode population. The nematodes effectively regulate the woodwasp population below damaging levels.
Additional Resources:
Eastern Forest Environmental Threat Assessment Center
Forest Encyclopedia, USDA Forest Service Research Station's
Forest Health Protection-USDA Southern Region
Forestpests.org
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