10000 General Insects is the most general of the codes all for insects, and should be used as a last resort if nothing more specific can be coded.Try to use a general or generic code only when no more specific code can confidently be used.Be aware that even among the generic codes, some are more general than others – e.g. 12000 Defoliators is more specific that 10000 General Insects.
It very difficult, even for specialists, to always know or predict the severity of pest effects on individual trees.We’ll try to give you our best information and opinions as we talk about specific pests, but in the field, you’ll have to use your own best judgment.Also, coding more that 1 pest or pest category (you can code up to 3) when appropriate may give the analyst more information that could be useful whether the pests act in concert with one another or they just happen to be there together.
There are five common pine bark beetle species in the South that all attack and kill pine trees. They are the southern pine beetle, black turpentine beetle, and three species of Ips or engraver beetles. Here we see the relative sizes of the different beetles.
Bark beetles have four life stages: egg, larva, pupa, and adult.
Lightning-struck pine trees are often attacked by pine bark beetles. In many cases, the lightning alone does not kill the tree; it is the bark beetles that attack after the strike that usually kill the tree.
External signs of pine bark beetle activity include reddish boring dust in bark crevices (left) and pitch tubes indicating where the beetles have attacked the tree. Pitch tubes in the three photos on the right include black turpentine beetle (left), Ips (center) and southern pine beetle (right). Note the size and color differences.
SPB make a characteristic winding S-shaped gallery pattern.
Some basic information about southern pine beetle.
When southern pine beetle (SPB) infestations (spots) are active and expanding, there will often be a gradient color change in the needles of infested trees. The most recent attacked trees will still have green needles and cannot be detected from the air. Next will be trees with yellow or fading foliage, then red needles, and finally bare trees. When this is present (usually in the summer months), it is a classic indicator of an active SPB spot.
Ips beetles seldom develop a discretespot that contains 5-10 trees or more. It is common for Ips to attack a single tree and not infest adjacent trees. Also, Ips will often kill the top of a tree first, leaving lower branches green. Trees rarely survive top kill by Ips. Trees attacked by Ips beetles often die from the top down.
Ips beetles tend to kill scattered trees in a stand.
Every tree has at least one leaf feeder.
Fall webworms build webbing around branches where they are feeding. They feed on more than 100 species of forest and shade trees including cypress (left photo).
Defoliation by fall webworm seldom causes serious damage to the tree. Their webbing is more of a visual issue. Activity from this insect can occur throughout the summer.
Gypsy moth is the only specific defoliator which has no damage threshold. If the insect is present, you can code it. Oaks, particularly white oak, are preferred species, but others are readily defoliated as well.These insects were introduced from Europe for their potential silk production and have since spread south and west. The are now threatening NC; moths are being consistently caught in traps in counties along the VA border, but populations have not become established enough to cause defoliation.The larvae are fairly easy to identify with their 2 rows of blue and red dots. There are 5 blue pairs behind the head followed by 6 red pairs. Larvae go through several instars from fairly tiny to about an average-sized caterpillar. They are present during June and July. They can totally strip the foliage off of large areas of trees.Moths are present for only a short period in late July and August.
Egg masses are not particularly diagnostic, but may be present over the winter and into spring before larvae hatch out in late May-early June. Larvae move up the tree to feed and grow. Eggs can be laid on tree trunks, rocks, campers, cars, etc.
Even though eastern tent caterpillar is given a specific FIA code, you should be aware that there are two common species of tent caterpillars in the South. The eastern tent caterpillar has a solid white line down the middle of its back, while the forest tent caterpillar has a “keyhole” or “footprint” pattern down the middle of its back. They both have one generation per year and the caterpillars appear in the spring. Eastern tent caterpillar builds a silken nest in branch junctions and feeds mainly on cherry, plum, and hawthorn. Forest tent caterpillar does not construct a distinct nest and feeds on a wide variety of hardwood foliage.
Both the forest and eastern tent caterpillars overwinter as eggs encircling twigs of host plants. The larvae hatch in the early spring as the leaves are unfolding from their buds. There is one generation per year.
This is an example of forest tent caterpillar defoliation in East Texas. Tent caterpillars are present each spring, but tend to be very localized. These caterpillars rarely cause a serious problem since the trees refoliate by early summer and only suffer minor growth loss. This was the largest foresttent caterpillar outbreak I (Pase) have ever witnessed in East Texas.
Theeastern tent caterpillar is especially fond of wild cherry, plum, and other trees in the genus Prunus. Distinct tents can be found in the early spring at branch junctions.
Larvae of the eastern tent caterpillar have a solid white line down the middle of their back.
From time to time, certain caterpillars will appear in the fall and feed on a variety of tree foliage. These rarely cause significant damage. There are more than just the ones listed here.
Walnut caterpillars are most commonly found on pecan. The larvae will congregate to molt (shed their skin) on the bole of the tree where they are feeding. The shed skins that are left behind may be present for a few months after the caterpillars have completed development. Pecan trees may be bare by mid-summer and into the fall. The caterpillar is harmless to people.
Pecan trees defoliated by walnut caterpillar.
Introduction to insects that bore in trees.
Red oak borer is a common wood-boring insect that attacks oaks in the red oak group almost exclusively. Historically, its population levels have never been high with most attacked trees sustaining only a few attacks. However in the late 1990’s – early 2000’s populations reached unprecedented levels in the Ozark Highlands and trees sustained thousands of attacks. The generally old age of the forest combined with several years of drought set the stage.With normally few attacks, little real damage is done to attacked trees beyond degrade of the lumber. The young larvae construct small areas of damage in the sapwood under the bark of just a few square inches. Larger larvae then bore deeper into the wood and upwards where they overwinter.
During the Ozark epidemic, trees died by the thousands after being heavily attacked by red oak borers. Frass and sawdust accumulated in deep piles around attacked trees. Entire stands were often decimated. Red oak borer attack and the Ozark epidemic can be considered a part of the larger oak decline syndrome (discussed later).
Adults emerge in the second year leaving round, pencil-sized holes in the bark. Surviving trees often have warty bark defects that cover over damaged areas and are evident for several years after attack. These are, however, very similar to damages from other causes or from branch stubs, etc.
NPTMs are mainly a pest of young pines. The larvae bore in the growing tips of terminal and lateral branches. They cause dieback and growth loss, but rarely kill trees. In the South they have 3-5 generations per year. The adult moths are very small.
Young pine plantation showing heavy tip moth infestation.
Asian longhorned beetle adults.
Comparison of Asian longhorned beetle and the native cottonwood borer.
Adult emerald ash borers. Ash is their only known host in the United States.
Life cycle of the emerald ash borer
Forest Health Panel - Insects - USFS and Jim Northum, AFC
USDA Forest Service, Southern Region, Forest Health Protection
Joe Pase, Texas A&M Forest Service
More than 1000 SPB spots detected
More than 80% treated or have gone inactive
Most treated with cut and leave due to problems
with the market
Funding from federal sources difficult to
organize and procure due to budget constraints
Thinning study says there are positive benefits
to thinning pulpwood size timber to reduce SPB
Southern Pine Beetle
Pine Engraver Beetles
Bark beetles have four
life stages: egg, larva,
pupa, and adult. Note
there are several larval
stages (called instars).
As the larvae feed, they
grow in size. Once
beetles reach the adult
stage, they never
increase in size.
Bark Beetle Activity Is Often Associated with Lightning Strikes
Some Common External signs of
Pine Bark BeetleActivity
Completes 7 generations per year
SPB outbreaks are cyclic, reaching outbreaks every 7-9
years, or longer (last outbreak in AR ended in 1995)
Multiple-tree infestations may expand rapidly without
Prompt direct control can reduce losses by 90%
Slow growing or injured trees are most prone to initial
Even healthy pines will be attacked and killed as
Young pine and Christmas tree
plantations (1-5 years old) are very
susceptible. Larvae bore in growing
tips of terminal and lateral branches.
Ronald F. Billings, Texas A&M Forest Service, www.Forestry Images
James A. Richmond, USDA Forest Service, www.Forestry Images
Young pine plantation showing
heavy tip moth infestation
Asian longhorned beetle has not yet been found
in the South, but the threat of introduction from
the northeast or Ohio is substantial.
DaleA. Starkey, Plant Pathologist and Forest Health
Monitoring Program Manager, USDA Forest Service,
Southern Region, Forest Health Protection
H. Joe Pase,(photography) Entomologist,Texas A&M
James D. Smith, Entomologist, USFA Forest Service,
Southern Region, FHP