Answers to frequently asked questions about
John L. Foltz, Forest Entomologist
University of Florida, Dept of Entomology and Nematology
Southern Pine Beetle suppression.
Q1. How can I recognize a beetle-infested pine tree?
Q2. How do I determine whether it is the southern
pine beetle or a different beetle infesting the tree?
Q3. Why is it important that SPB-infested trees
be treated as soon as possible?
Q4. What are acceptable ways to treat a beetle-infested
Q5. The needles are still green, can't we save
Q6. Why should pines be felled and cut into
short sections before applying an insecticide?
Q7. Should I spray my pine trees to keep beetles
from attacking them? Are systemic insecticides effective?
Q8. Why do we need an area-wide program to suppress
southern pine beetle outbreaks?
Q9. What are the benefits of having a mandatory
area-wide suppression program?
1. How can I recognize a beetle-infested pine tree?
Most infested pines are discovered when we see that needles throughout
the crown have changed from the normal dark green to a light green, yellow
or red. On close examination of the trunk we then see holes about the diameter
of a pencil lead where beetles have chewed through the bark. A resistant
tree will flood the attack site with resin resulting in popcorn-like pitch
tubes on loblolly pines and brown runny streaks on slash and longleaf pines.
A moisture-stressed tree may have no resin and then we have to look closely
for boring dust on bark ledges, leaves, and spider webs around the base
of the tree. A homeowner who regularly examines yard trees may find the
boring dust or pitch before the needles fade, thus allowing more time to
treat that tree and protect surrounding trees.
2. How do I determine whether it is the southern pine
beetle or a different beetle infesting the tree?
There are five different species of bark beetles which infest pine trees,
either individually or in concert. To identify the species present we remove
some bark and look at the size and shape of the beetles and their associated
egg galleries. The southern pine beetle (SPB) is the smaller of the two
beetles with rounded rear ends. It is about 1/8 inch long, about half the
size of a grain of rice, while the larger black turpentine beetle (BTB)
is about 1/4 to 3/8 inch long. The three Ips beetles all have scooped-out
rear ends with small spines around the margin and range in length from
1/10 to 1/4 inches. Southern pine beetles make winding, intersecting egg
galleries packed with boring dust. Black turpentine beetles start with
a short horizontal gallery and then turn and tunnel downward toward the
ground. Galleries of the Ips beetles are distinguished by 1 to 4 clean
galleries prepared by females radiating out from the nuptial chamber made
by the male where he attacked the tree.
3. Why is it important that SPB-infested trees be treated
as soon as possible?
The southern pine beetle at times is an exception to the general rule that
bark beetles are generally scavengers of dead or severely weakened trees.
When populations are high, this species will mass attack and kill trees
that otherwise would live for many additional years. Because this species
can develop from egg to reproducing adult in as little as four weeks, we
have relatively little time to detect an infested tree and keep the brood
from dispersing to colonize new trees.
4. What are acceptable ways to treat a beetle-infested
There are many ways to prevent beetles from developing in and dispersing
from infested bark. Sometimes a cluster of infested trees can be cut and
sold to a wood processor where the bark is quickly removed and burned
while the wood is processed for pulp or lumber. In urban situations,
however, a homeowner must often contract a tree service to cut a tree
and kill the beetles. Unfortunately, no insecticides are currently
registered and effective at killing beetles as they emerge. Burning and
burying infested bark are other ways to control beetles.
5. The needles are still green, can't we save the tree?
A tree is doomed once bark beetles colonize and destroy its inner bark.
Without this phloem tissue, the carbohydrates produced in the needles cannot
nourish the living cells in the roots. Without living roots to provide
water and nutrients to the crown, the needles dry out and die. The blue-stain
fungus carried by beetles often hastens needle death by growing into the
sapwood and plugging the water-conducting cells.
6. Why should pines be felled and cut into short sections
before applying an insecticide?
Insecticides kill beetles in part by penetrating the bark and killing the
developing brood and in part by killing beetles as they chew out before
flying away. For the area-wide suppression program to be effective as soon
as possible, it is important that all infested bark be sprayed to the point
of runoff. By cutting the trunk into easily rolled sections and by adding
a conspicuous coloring agent to the insecticide, the applicator is able
to assure the necessary coverage.
7. Should I spray my pine trees to keep beetles from attacking
Are systemic insecticides effective?
Where an area-wide suppression program is underway it is rarely necessary
to spray trees to protect them from future attacks. One case where a homeowner
may wish to invest in a protective spray is when lightning, construction,
or other injury weakens a tree and it produces terpenes which might attract
beetles. In such cases the homeowner must contract a pest control operator
who has the appropriate license and equipment for putting a registered
insecticide at least 35 feet high on the trunk.
With regards to systemic insecticides, no research test has ever shown
systemics to be anywhere nearly as effective as insecticide
sprayed on to the bark. Systemic insecticides apparently do not remain in
the phloem tissue in sufficient concentrations to affect beetle attack
8. Why do we need an area-wide program to suppress southern
pine beetle outbreaks?
Southern pine beetles develop from eggs to reproducing adults in as little
as four weeks except during the cooler months of winter. Young females
may then fly several miles before attacking new trees and laying as many
as 100 eggs before dying. When populations are high, thousands of beetles
may attack a tree in one afternoon and overwhelm its ability to resist
colonization. This combination of a high reproductive rate, great dispersal
ability, and aggregation to mass attack trees requires that all infested
bark over a large area be treated so that we can reduce beetle numbers
below the threshold needed to overcome tree resistance. Leaving just 10
or 20% of the trees untreated may allow an outbreak to expand and persist
for many months.
9. What are the benefits of having a mandatory area-wide
The principle direct benefits of an area-wide suppression program are that
fewer trees will be killed and fewer dollars will be spent to remove or
treat infested trees. Another benefit is that protective chemical treatments
are unnecessary, saving the economic and environmental costs of insecticide
Additional information about the southern pine beetle can be found at:
Prepared by John L. Foltz,
19 Oct 1997. Last modified 17 May 2004.
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