The battle of the beetles
Methods for the Prevention and
Treatment of Bark Beetles
Provided as a Public Service by
The Tano Road Association
A Real Life Bark Beetle Scenario Along Tano Road… .
“… … one property owner ignored his dying piñon trees. After threeweeks, the bark beetle eggs hatched, the larvae matured, exited the tree,and spread to his other piñon trees. By summer’s end, he had lost 50%of his piñon forest, and the beetles spread to his neighbors’ property.
… … and another property owner, concerned about his dying piñon trees,hired a tree firm to cut and mulch them. He instructed that the mulch bespread under the living piñon trees. The eggs, larvae, and beetlessurvived the mulching, and infested the remaining piñon trees.
… … yet another property owner hired a tree firm to cut down his dyingand dead piñon trees. He instructed them to wrap the cut wood in blackplastic in hopes that the accumulated heat from the sun would kill eggs,larvae, and beetles. The beetles quickly found an exit from the plasticand infested other trees. Over the summer, many of the eggs hatched, thelarvae survived the heat, and the beetles escaped.”
Other nearby owners in this area sought advice about how to protect theirproperty from the Bark Beetle infestation. This booklet of guidelinesexplains step by step what they learned, how they applied what theylearned, and the happy results.
The Battle of the Beetles
A Summ ary of Guidelines and Methods for the Prevention and
Treatm ent of Bark Beetles1
BARK BEETLE 101, A BEGINNER COURSE
This is a “best practices” summary of the prevention, treatment andmediation of Bark Beetle infestation. There are many differentapproaches and methodologies in dealing with Bark Beetles, anddepending to whom you are talking, each will have particular value.
However, we have taken the more conservative approach whichgenerally represents the best practice among professionals. We do not
1 Copyright 2006, The Tano Road Association. No part of this booklet may used or reprinted in anyform , including electronically, without the express perm ission of The Tano R oad Association.
argue that there are no other methods, only that the methods we suggestare generally found by professionals as producing the most consistent,effective results.
Our particular type of beetle is the Ips Bark Beetle borer [Six-spinedengraver, Ips calligraphus calligraphus G
Bark Beetles are nearly always fatal according to the New Mexico StateUniversity Extension Office because even if the beetle invasion itselfdoes not kill the tree, the beetle carries the blue stain
fungus whichalways kills the tree.
In the view of the Extension Office, there is no cure once a tree is
infested and an infested tree should be cut down and hauled aw ay
im m ediately
. The Extension Office notes that infested trees must not be
chipped and used as mulch since some beetles will survive the chipping
process and simply breed in the mulch, often at an accelerated rate of
reproduction. Further, during the chipping process, the beetles will
swarm out of their nests in the infested tree and go immediately to
neighboring piñons. This is also the collective wisdom of most
entomologists and arborists.
But why Bark Beetles this year and not another? Simply, the reason isstress as a result of the drought. Strong piñons with large well developedroot systems seek out what little water is available while weaker piñonscan not. The weaker piñons struggle to just survive, producing little newneedle growth and few new candles, conserving energy to the rootsystem. The effect in this “survival mode” is a piñon with severelyreduced pitch sap flow in the tree. It is this reduced sap flow whichpermits successful Bark Beetle infestation In a Darwinian sense, this isnature’s way of eliminating weak trees and reducing demand on analready scarce water supply.
The Bark Beetle has, like most insects, a definite life-cycle. They arepart of a larger category of insects known as “tree borers”. Adult malesbore into the bark of the piñon, generally on the main trunk initially. Theholes are about 1/8 of an inch and easily seen by the naked eye. Oncepast the bark of the piñon, the males enter the outer cambium of the treeand begin chewing tunnels up and down the cambium. These tunnels arethe mating chambers for the female Bark Beetle.
Generally, the stronger trees do not attract heavy infestations of BarkBeetle since if a male Bark Beetle does bore an entry hole into a healthypiñon, it is almost immediately closed over by a rich flow of piñon sap,expelling the Bark Beetle and sealing off the entry hole. In subsequentyears, these sealed off entry holes will appear as dark amber colored sapnodule, hard to the touch. Because the male Bark Beetle has notsuccessfully prepared the mating tunnels in a healthy piñon, no furtherinfestation occurs. It is for this reason that adequate water supply,essential for pitch sap flow in piñons, is a key factor in preventing BarkBeetle infestation.
It is said by arborists and scientists alike that the male Bark Beetle thenemits a pheromone which signals to female Bark Beetles the readiness ofthe prepared mating tunnels in the infested piñon tree. The females enterthe tunnel network, lay eggs in the tunnels which then hatch and beginfeeding on the pitch sap of the piñon. The male exits the tree at this timeand will travel no more than about 60 feet [although they can fly up to 3miles but rarely do] to another piñon under stress and the process beginsover again. The female dies after laying her eggs. The typical lifecycle ofthe Ips Beetle is 6 to 8 weeks in the warm weather periods.
In the crevices of the tree and bark, you will often see the “saw dust”tailings of the beetles which are generally from the tunneling activity ofthe newly hatched larvae. When this is evident the piñon is alreadyheavily infested. Prior to this, however, you may only see the entry holeswhich would indicate eggs may have been laid by the female but havenot matured to larva yet and the evidence of the saw dust from thetunneling has not occurred.
Once the eggs are hatched, the larvae will begin feeding on the pitch sapof the piñon and extend massive networks of horizontal tunnels aroundthe entire circumference of the piñon [termed girdling] to tap-off allvertical sap flow as a food source for the larvae colony. It is because ofthis activity that evidence of heavy infestation of Bark Beetle is easilynoted by yellow or brown needles on the piñon from the top downresulting from the starved sap supply of the tree.
To make matters worse, the Bark Beetle is host to the blue stain fungus[Ceratocystis ips
(Rumbold) C. Moreau ] which attaches itself to theundercarriage of the beetle shell and is deposited into the phloem of the
piñon. Santa Fe's integrated pest manager, Fabian Chavez, notes that thefungus can clog a tree's waterways, rendering watering ineffective intrees that have already been infested with the fungus even though thebeetles may have left the tree or been killed by pesticide.
However, as Dan Herms, an entomologist at Ohio State University notesnot all Bark Beetles carry the fungus and so it is not a given that once abeetle infestation occurs, the fungus has been introduced. It is for thisreason that systemic treatments can be effective. In a laboratoryenvironment, the fungus can be rather easily killed. However, at present,there is no science which has identified a systemic fungicide treatment tokill the blue stain fungus in the piñon.
Further, Winter weather does not always provide relief from infestation.
Chavez said that even low temperatures don't always kill the beetlesbecause they have a substance in their bodies that is also found inantifreeze that protects the beetle from freezing in the cold.
Other factors can also put a tree under stress. Needle tip fungus iscommon among piñons and while rarely will kill the tree by itself; it willplace the piñon under stress and therefore make it susceptible to BarkBeetle. Pitch Moth, another common pest to the piñon, will generallyonly kill the piñon over a period of years but will also put the piñonunder stress as well.
Twig beetles, over time, kill the new twigs at the tips of the limbs.
Remove limbs and twigs that are infested, and dispose of them before thelarvae hatch.
Of greater nuisance is mistletoe, the yellow-green growth sometimescalled “witch’s broom” that invades both piñon and juniper trees. Piñondwarf mistletoe (Arceuthobium divaricatum) is a small, parasitic plant.
The external shoots are yellow-green to brown, have small scale-likeleaves at the nodes of shoots, and are perennial. Mistletoe extractsnutrients and water from the branches of the host tree eventually killingthe branch. If left unattended it will not only kill the tree but spread toother nearby trees.
The only sure way to rid the tree of mistletoe is to remove the infestedbranch. Removing only the visible mistletoe does prevent further spore
dispersion in the Autumn months but the actual infection remains.
Add any of the stress factors together and you multiply the susceptibilityto Bark Beetle and the piñon’s ability to fight off an infestation.
Six-spined engraver, Ips calligraphus calligraphus
PREVENTION AGAINST BARK BEETLE
As we have discussed, watering your piñons well, especially during thewinter months, is an effective defense against Bark Beetle.
Understanding the life cycle of the Bark Beetle, rich sap flows in thepiñon resulting from adequate watering seal off initial entry holes madeby the male and prevent infestation.
Be sure to build holding wells around the trunk of the piñon [ideally outto the drip-line of the tree] to allow for maximum soaking of the tree.
Generally, two fills of the well should be considered an adequatewatering at a time.
u Topical Pesticide [Spraying]
In addition, local nurserymen will suggest spraying with the insecticide
Sevin or the environmentally friendly permethrin. Spraying can be
another effective tool against Bark Beetle depending on when the
spraying is done. Spraying must be done prior to infestation. Since
spraying is topical, that is, dried into the bark of the piñon, spraying
after infestation will not kill any beetles
already into the cambium of
Spraying coats the bark of the tree. W hen the male Bark Beetle beginsmaking an entry hole in the outer bark of the piñon, the insecticide isingested by the beetle which dies from paralysis. But if the spraying istoo old [anywhere from 2-6 months efficacy] then the tree must be re-sprayed to extend the protection. Spraying once in the Spring and againin mid-Summer can serve as an effective preventative.
Throughout Colorado, permethrin has been used for years instead ofSevin since it has been shown to be well tolerated by wildlife.
Permethrin is made from a concentration of the chrysanthemum flower,and when highly distilled, it is extremely effective as an insecticide.
Synthetic forms have now been formulated with equal effectiveness.
Once it dries it is safe for pets and wildlife to be around. Permethrin, likeall insecticides, is a topical spray to the bark. It is only a preventative,prior to an infestation of the Bark Beetle. To repeat, spraying a tree after
System ic Pesticide
Once the Bark Beetle is inside the tree the only logical way to attempt tosave the tree would be with some type of chemical which enters the sapsystem of the tree and kills the pest feeding on the sap inside the tree.
This type of treatment is termed systemic.
Here is the problem with systemic treatments. Bark Beetles feed on thesap and make extensive tunnels where newly hatched larvae feed; sapflow can no longer reach the extreme upper portions of the piñon. Thatis why an active infestation of Bark Beetle is visible from afar by thefading, dying needles from the top of the piñon downward. In effect, theyare strangling the nutrient flow to the tree.
In order for a systemic treatment to be effective, there must still be sapflow in the tree to carry the insecticide to the infested areas. If theinfestation is too far advanced, feeding the insecticide to the roots willsoak into the root system but not go up the trunk where the Bark Beetleis nesting, so prompt application is everything. As soon as anyinfestation is noticed, immediate application is required followed byheavy watering to maximize sap flow uptake. It is a race against time, butit can be successful.
Even though our Extension Office does not recognize any such systemictreatment, several products are currently available which have hadfavorable results. In any event, it can be an effective preventive measure,particularly in concert with other methods.
Using a systemic pesticide has added benefits in that it also attacksinfestations of pitch moth and tip beetle [a cousin of the Bark Beetle],and with an extended residual efficacy [up to 12 months] systemicpesticides can provide longer term protection.
u Root-Saturation Systemic Pesticide
Perhaps the most effective systemic treatment against a variety of piñonmaladies is produced by Bayer AG. It is the systemic pesticideimidacloprid [Merit, Bayer Advanced Tree and Shrub Insect Control]
which is fed into the piñon via the root system. The application rate is 1oz. of the Bayer liquid pesticide per 1 inch of piñon trunk circumference.
Using a common cloth tape measure, a piñon with a trunk circumference of 32 inches [10 inch caliper] would require 32 ounces of pesticide,diluted in 1-2 gallons of water and applied at the root base of the tree.
W hen to apply the Bayer AG is mostly a matter of weather. The treemust be in sap flow, or in its growing cycle, in order to insure that thepesticide is brought up into trunk and branch system of the piñon.
Generally this is in the warm weather period of Spring. It must be noted,however, that it may require 4-6 weeks to be fully distributed throughoutthe piñon and therefore that length of time will be required to achievemaximum protection. Warmer weather accelerates the sap flow so thepesticide is fully distributed in the piñon more quickly. However, waittoo late and the risk of Bark Beetle infestation increases. Apply in Aprilor May for ideal results.
In view of the time required to fully distribute the Bayer AG throughoutthe piñon, using it when an infestation is discovered may not allowenough time, or sap flow uptake, to kill the beetle before the tree dies. Itis a gamble, but may be judged worth the expense.
There are several resources to buy the Bayer AG: Newman’s Nursery,Paynes Nursery, Santa Fe Greenhouse, Home Depot and Walmart. Aquart [32 oz.] costs $32 at normal retail but can be found at discount attimes as low as $18. Newman’s also carries the one gallon size for $75and has been known to offer quantity discounts at the case level [12quarts or 4 gallons].
Bayer AG, even as a concentrate, can become expensive depending onthe size of tree to be treated. Generally, trees are selected because ofprevious illness, they are recent transplants, or they are particularspecimens of landscape importance. To treat every piñon on a propertywould be very costly.
u System ic Pesticide Injection
There is a systemic treatment which uses an injection system placed inthe trunk of the piñon at about chest height. This patented system wasdeveloped by Dr. Roger Webb who founded Tree Tech in Morriston,Florida. The company is located at:
Tree Tech950 S.E. 215th AvenueMorriston, Florida 326681-800-622-28311-352-528-5335http://www.treetech.net
Dr. W ebb advises that he can sell his restricted use product only tolicensed professionals. The insecticide is highly toxic and under theregistration of the EPA.
The only licensed company west of the Mississippi is located inAlbuquerque:
NARROW LEAF, INC.
100 A Pueblo Road N.W .
Albuquerque, New M exico 87114505-897-1172
There are 3 patented products from Tree Tech which can all effectivelykill Bark Beetle:
Ø Vivid II
Because piñon sap is pitch-like, water based injections will notwork… … the water will not penetrate the sap. As a result, Dendrex,which is water based, is not effective for our piñons.
Vivid II and Harpoon are both petroleum based injections and will travelin the pitch sap of the piñon. Some recommend using a combination ofboth Vivid II and Harpoon on each infested piñon with Bark Beetle. For
example, in one large piñon 16 injectors were used and, at $20 perinjection, the treatment becomes expensive. Smaller piñons require less.
As a result, a careful evaluation is required so that the investment isprudent. Some piñons may have become too infested to be saved becausethe sap flow may have been too restricted for the insecticide to travel upto the extremities of the piñon. U se of injection in this instance wouldprovide little if any benefit.
Successful injections generally will travel systemically throughout thecirculatory system of the tree over a period of days. Trees with weak sapflow may take longer to make the entire circuit and Bark Beetle activitymay continue in selected areas until the insecticide can reach those areas.
A successfully dispensed injector will collect clear tree sap of the piñonback inside the injector [a kind of back-flow] which is evidence theinsecticide has been fully integrated into the circulatory system of thetree. The holes drilled for each injector are not a threat to the piñon asthe tree will sap-over the hole immediately following the removal of theinjector.
The advantage of systemic pesticide injection is that the response time,when effective, is a few days rather than the weeks required by the root-saturation method.
Again, systemic injection can be expensive [about $20 per injection].
Spaced 4 inches apart around the circumference of the trunk of the tree atchest height, 4 injections would treat a 5 inch trunk at chest height.
However, to cut down and haul off a large tree could easily cost $100and to treat this large specimen tree would cost about the same andmaybe save it. Some specimen trees can not even be replaced, [even at$8,000-$10,000 which is what Coates estimates some are worth,]because they simply are not available, and even if they were available,the risk of transplant at such a size is significant.
W ith systemic injection the piñons with the severe infestations willprobably result in a total needle-loss but as long as the twigs are flexiblethere is evidence of sap flow and the tree could survive. New needlegrowth could come as early as October or as late as next spring andwatering trees treated with Vivid II/Harpoon increases the effectivenessof the injection.
The injectors stay in the tree for 36-48 hours. Narrow Leaf must alsoremove each injector as a part of their EPA license and comes back up toSanta Fe in a day or two, which is included in their fee.
One crude test to verify the Bark Beetles have been killed is to just listenfor them. Active infestations, particularly at the tunneling stage, producea faint clicking noise where the beetles are currently “working”.
Narrow Leaf stated the U.S. Forest Service recently purchased over $8
million of the Tree Tech system to treat select specimen trees in national
W hile there have been varying levels of success with systemic pesticides,
both injection and root based applications, topical pesticide application
has been quite effective. You should consider that each of the methods
suggested should be part of an overall program to protect and treat piñon
The best protocol is to prevent infestation
in the first place. This is best
Periodic water soaking the root base, application of systemic pesticide imidacloprid [Merit, BayerAdvanced Tree and Shrub Insect Control] in April or May, application of topical pesticide [spraying] of permethrin in earlySpring and mid-Summer.
DISPOSAL OF INFESTED TREES
Once piñons are infested, the “best practices” protocol is to cut themout right away to prevent further infestation to nearby trees, includingyour neighbor’s.
Immediately remove to the landfill all debris and cuttings from yourproperty.
Do not chip the dead trees up, no matter who advises you otherwiseas this will cause swarming by the remaining beetles which are not killedby the chipper, most of those fleeing as the wood is being fed into thechipper.
It is not recommended to “solarize” your infested cuttings and debris bycovering them with a 6 mil black [or clear] plastic blanket and letting theheat build-up by the sun kill the beetle.
Note: Our Northern New Mexico daytime temperatures are notconsistently high enough for long enough to kill beetles deepinside the wood cuttings. The rapid cool off of our nighttimetemperatures throughout the year makes it unlikely the requiredhigh sustained temperatures can be reached for therecommended 30 days of a “solar oven effect”. Some beetlesmay be killed in the smaller branches, however, those nestingin the larger main trunks are more likely to survive and pose athreat of further infestation. Furthermore, it is very difficult tokeep the wrapping air-tight and escape-proof.
It is essential to remove the dead tree from the property altogether.
Burning infested wood in your stove or fireplace can result in other risks.
Of course the beetle will not survive the fire. However, even if thetemperature outside has been consistently below freezing for severalweeks, Bark Beetles can still be alive and feeding on the recently felledpiñon in your wood pile and, as a result, they may infest healthy treesnearby. Using this firewood of infested piñons may be a false economy.
BARK BEETLE CHECK-LIST2
The last major Bark Beetle infestation was 2 years ago when entireforests of piñons were lost to the beetle. It was also a time of severe andsustained drought. This recent infestation rivaled that of 50 years ago.
In an effort to gather the most effective methods for managing the beetleinfestation, there are many different suggested approaches from a widevariety of sources and at times conflicting points of view. This maysimply be the result of the fact that the last major infestation of 50 yearsago was so long past that the methods which were used then are out ofdate.
This Check-List purposely takes a conservative, “best practices”approach, and is a combination of the wide range of sources noted here.
Further, geography is also a factor. For example, “solarizing” [see item5 below] may be very effective in Albuquerque but not recommended inSanta Fe’s higher altitude. While there are alternate methods availablefor handling a beetle infestation, those methods may pose a risk forcontinued infestation of nearby piñons and are not recommended here.
Here are some reminders when dealing with Bark Beetle infestation:
2. Remember, Bark Beetle infestation is a community
Bark Beetle is in the tree only 21 days, and further infestation can bewidespread before it is clearly obvious, so inspect often and act quickly.
3. Inspect your piñons frequently, especially after temperatures
2 Sources: New Mexico State University Cooperative Extension Service,“Conifer Pests in New Mexico”, 1977; USDA, United States Forest Service,Southwestern Region; Tom Sharpe, The Santa Fe New M exican, August 13, pg.
A-1 & August 14, pg. A-2 and Dr. Erica Elliot, September 8, 2002, pg. F-7;W es Smalling, The Santa Fe New Mexican, September 24, 2002, pg. A-5; W renPropp, The Albuquerque Journal, September 27, 2002, pg. A-1; Fritz Thompson,The Albuquerque Journal, September 29, 2002, pg. A-1, A-10; Dr. RogerW ebb, Tree-Tech Injection Systems, M orriston, Florida; Narrow-Leaf Inc.,Albuquerque, New M exico; Santa Fe Greenhouses, “Dealing W ith The BarkBeetle”; Coates Tree Service, Santa Fe, New M exico; Roy’s Tree Service & PestControl, Santa Fe, New M exico; Newman’s Nursery & Greenhouse, “TreatingPinons with Bark Beetle”, August, 2002, Santa Fe, New M exico.
ð Look for yellowing or hay-colored needles whichsignal that the tree is or has been infested.
ð Even if the needles are green, inspect the bark for reddish-brown sap formations (pitch tubes), tiny one sixteenthpinholes in the bark, or rusty brown sawdust in the crevices oron the ground. ð Listen for clicking noises from the tree, and sniff forstrong resin scent. ð Any of these symptoms signal that the tree has beeninfested.
4. When you detect an infestation, act quickly and decisively.
5. If you catch the infestation early enough, you may be able
to use a systemic insecticide to kill the beetle. Earlydetection is the key here. Early stage is defined as thecondition where entry holes are evident but the “saw dust”residue is not yet present.
6. If you are trying to save the tree by using a systemic
insecticide, regular, deep-soaking watering will muchimprove survival.
A pply slow drip irrigation to important trees during
all seasons. If you haven’t installed an automatic irrigation
system, then a water-efficient, effective, and inexpensive method
is to purchase soaker hoses ($8 each) from W al-Mart, Home
Depot, or your garden supply. Lay a soaker hose under the tree’s
drip line, attach to garden hose, and turn faucet only one-fourth
turn. Let run three or four hours. If water accumulates on the
ground, reduce the flow.
7. Successful systemic treatment can be evidenced by flexible
twigs and the emergence of new needle growth on the outerlimbs.
8. If the tree is too far gone, usually evidenced by no green
needles, no sap flow to upper limbs and brittle twigs, then
the tree should be cut down
in large sections and
from the property, immediately. Do
not leave the infested tree standing because the beetle
larvae will hatch, exit and kill other trees.
9. Take Note:
It is not recommended to keep the cut up dead
trees on your property under a plastic blanket.
10. Remove the dead tree from the property altogether.
11. Do not chip
or shred the dead tree
in order to use it as
mulch. The beetles will swarm while chipping and infestother trees on your property. Further, using the chips asmulch only provides a breeding ground for further beetleinfestation.
12. Rake up
all the dead needles
under the tree, place them in
plastic bags and remove them from the property.
13. Firewood ordered for winter should only be seasoned wood
[1 year old] where sap has hardened and the wood driedout. Fresh cut piñon is an ideal breeding ground for BarkBeetle. If you already have unseasoned firewood, cover thestack tightly with plastic tarps or sheeting.
14. Do not collect
piles of tree cuttings
and tree debris, even
healthy ones, on your property as they can also serve asnesting grounds for the beetle.
15. In early spring, just after the last freeze, trees can be
with Sevin or permethrin to provide protection
against new Bark Beetle infestation. Depending on the
concentration of the spray and thoroughness of the
spraying, protection will last from 2 to 6 months. The
proper concentrations can be applied only by a licensed
nurseryman or arborist.
- Recent studies indicate that proper spraying is 90%effective in protecting the tree.
16. Spraying after an infestation will not kill the beetle already
Do not attempt to save the infested tree by spraying or
watering, it will not survive. Because the Bark Beetle is a
carrier of the Blue Stain fungus, fungal spores quickly
germinate and infest the sapwood, blocking the flow of water
throughout the tree. Generally speaking, you cannot save an
infested tree, unless very early detection allows the successful
use of systemic pesticide injections.
14. Maintain the health of your trees, living and dead:
- Remove all dead trees within sixty feet of your house.
- Remove all dead branches on trees within thirty feet ofyour house.
- Remove live tree branches close to the ground (four to six feet) from all trees within thirty feet of your house for fireprevention- Remove all debris from the ground within thirty feet ofyour house. This does not include the matted needles “duff”under healthy trees, but does mean all needles from underinfested trees.
15. If you hire someone to spray or remove your trees, check
their credentials and their references. There are widevariances in the fees and services offered. Sometimes youget what you pay for.
16. Spraying after an infestation will not kill the beetle already
Ips Bark Beetles in the South
M ichael D. Connor¹ and Robert C. W ilkinson²
¹Entomologist, USDA Forest Service, Southern Region, State and
Private Forestry, Forest Pest Management, Pineville, La.
²Professor of Forest Entomology, Department of Entomology and
Nematology, University of Florida, Gainesville, Fla.
There are three principal species of Ips
bark beetles (Coleoptera:Scolytidae) attacking pines in the Southern United States: theeastern six-spined engraver, Ips calligraphus calligraphus
(Germar); the eastern five-spined engraver, Ips grandicollis
(Eichhoff); and the small southern pine engraver, Ips avulsus
(Eichhoff). From 1973 to 1979, these three Ips
species caused theloss of an estimated 6.6 million board feet and 1.1 million cords ofpine timber in the South.3 The only insect to kill more pine timberin the South is the southern pine beetle, Dendroctonus frontalis
Zimmermann, which often attacks trees in combination with one ormore of the three Ips
species, and the black turpentine beetle,Dendroctonus terebrans
beetles usually attack weakened, dying, or recently felled trees andfresh logging debris. Large numbers of Ips
may build up when naturalevents such as lightning storms, ice storms, tornadoes, wildfires, anddroughts create large amounts of pine suitable for the breeding of thesebeetles. Ips
populations may also build up following forestry activities,such as prescribed burns that get too hot and kill or weaken pines andclear-cutting or thinning operations that compact soils, wound trees, andleave large amounts of branches, cull logs, and stumps for breeding sites.
Two subspecies of Ips Calligraphus
are recognized: Ips calligraphusponderosae
(Swaine) and Ips c. calligraphus.
The distribution of Ips c.
ponderosae, I. c. calligraphus, I. grandicollis,
and I. avulsus
within theUnited States is as follows: Ips c. ponderosae
is a western subspecies andwill not be discussed further in this leaflet; Ips c. calligraphus
isprimarily an eastern subspecies that occurs naturally from southernCanada to the Gulf of Mexico and a small population has apparentlybeen introduced into California; Ips grandicollis
is also an
easternspecies found from Canada south to the Gulf and on some of theCaribbean Islands and accidental introductions have also establishedpopulations in South and Western Australia; and finally, Ips avulsus
isthe only species confined almost entirely to the Southern United States.
Signs of Infestations
3 Data taken from yearly unpublished reports of the Southern Forest Insect Work Conference,calendar years 1973-79, Survey of D am age C aused by Forest Insects in the S outheast.
Trees attacked by Ips
bark beetles, whether in the forest or around thehome, are usually noticed when needles turn yellow or red. Upon closerexamination, infested trees will have dry, reddish-brown boring dust inthe bark crevices. Some trees may have dime-size or smaller, white toreddish-brown projections, called pitch tubes in the bark crevices.
Pitch tubes are a mixture of pitch and bark particles pushed out by theattacking beetles. The center of the tube contains a hole through whichthe adult beetle enters the inner bark. If no hole is present in the pitchtube, the beetle attack was unsuccessful. Vigorous trees attacked by afew adults often produce enough pitch to either drown the beetles in theinner bark or push them back out of their entrance tunnels. If the barkaround a hole containing dry boring dust is carefully cut away, thebeetles can often be seen in their tunnels within the inner bark.
beetles carry numerous spores of a bluestain fungus,Ceratocystis ips
(Rumbold) C. Moreau, in their gut. W hen the adultsattack trees or logging slash, the bluestain spores are excreted with beetlefeces into egg galleries, where the spores germinate. Bluestain funguscolonies grow into the outer sapwood of infested pines, stopping theupward flow of water to the tree crown. Lack of water causes needles towilt and die, gradually changing their color, from dull green to yellowgreen to red brown. These color changes may occur in 2 to 4 weeksduring the summer, but take several months in the winter.
W hen Ips
beetles leave a tree, their emergence holes look like scatteredshot-holes on the surface of the outer bark. During hot weather, beetlesusually leave a tree by the time the foliage turns red brown. During eithercool or moist weather, the beetles may leave while the foliage is stillgreen. Therefore, the best way to confirm the presence of Ips
beetles in atree is to remove several apparently attacked sections of bark todetermine if any beetle life stages are present.
Newly emerged adults of the three Ips
species are light orange brown incolor; mature adults vary from dark red brown to almost black. Theposterior of Ips
adults looks as if it has been cut off at an angle andhollowed out. Close inspection with a magnifying lens shows that Ips
adults have a number of spines on the outer side of each wing cover nearthe posterior. In the South, most pine bark beetles that could be confusedwith Ips
lack spines and have rounded rear ends that are not hollowedout.
In the adult stage, the three Ips
species can be distinguished by their sizeand the number of spines. Ips calligraphus
adults are about 5 mm (1/5in) long and have 6 spines on each side near the posterior. Their eggs areoblong, pearly white, and about 1 mm (1/25 in) long by 0.5 mm (1/50 in)wide. The grub-like larvae are small, whitish, and legless, with orange-brown heads up to 1 mm (1/25 in) wide. The pupae are waxy white andsimilar to adults in size. The eastern six-spined engraver commonlyinfests thick-barked pines and usually attacks portions of trunks that are10 cm (4 in) or more in diameter. This is often one of the first barkbeetles to attack drought-stricken trees.Ips grandicollis
adults are about 4 mm (1/6 in) long and have 5 spines oneach side. The eggs are about 0.9 mm (1/30 in) long by 0.5 mm (1/50 in)wide, and larvae have heads up to 0.8 mm (1/32 in) wide. Pupae arewaxy white and similar to adults in size. Recently felled trees and freshlogging debris are favored breeding material. In standing trees, thisspecies is usually found in the upper trunk and basal portions of largebranches.Ips avulsus
adults are about 3 mm (1/8 in) long and have 4 spines oneach side. The wing covers of Ips avulsus
are lighter brown than thethorax. The eggs are about 0.8 mm (1/32 in) long by 0.46 mm (1/55 in)wide, and larvae have heads up to 0.7 mm (1/36 in) wide. Pupae arewaxy white and similar in size to adults. Fresh, thin-barked loggingdebris, such as the upper portions of branches and tops of pines, is ofteninfested. The crowns of large, living trees may be attacked and partiallyor completely killed. It is common to find one or more species of Ips
, aswell as other pine-infesting beetles, inhabiting various parts of the sametree.
It is usually the male Ips
that initiates the attacks on living pines orlogging debris by boring an entrance tunnel through the outer bark andexcavating a small, irregular nuptial chamber within the inner bark.
Generally one to four females are attracted to the male beetle in thischamber, where mating occurs. From this chamber, each female thenbegins constructing an egg gallery. These egg galleries usually follow theunderlying wood grain, often resulting in Y- or H-shaped gallery patternsin the inner bark.
Females lay their eggs in niches that are chewed out at intervals on eitherside of the egg galleries, and cover them with plugs of inner bark. During
warm weather, larvae emerge from the eggs after a few days and makeindividual tunnels or feeding galleries in the inner bark.
The feeding galleries extend from the niches in the egg galleries,enlarging as the larvae grow. Mature larvae stop feeding, turn chalkywhite, and pupate at the end of their galleries, or sometimes in roundedpupal chambers. Here the pupae change to young adults. The new orbrood adults make short, winding tunnels in the inner bark, consumingbluestain fungus fruiting bodies before maturing and boring out throughthe bark to repeat the life cycle.
One generation of Ips
may be completed in approximately 21 to 40 daysduring the summer or may require several months during the winter.
Under warm conditions, the short life cycle allows populations toincrease rapidly. Because very little development takes place belowabout 15° C (59° F), Ips
is not a serious problem during cold weather.
Integrated Pest Managem ent
Beetle-caused damage can be reduced through one or more prevention or
An important factor in determining the incidence and
severity of Ips
activity is the amount of suitable host material available
for breeding. Forestry practices that reduce the amount of such material
help serve as preventive control measures.
The following practices are recommended during logging or thinning
Use as much of each crop tree as possible. Avoid leaving logging
debris in contact with or close to residual pines.
Remove harvested timber from a stand as soon as possible,
especially during warm weather. Whenever feasible, stackharvested timber or pine firewood away from living pines.
Minimize the damage to future crop trees that is caused by
logging equipment and vehicles. When thinning, use the lightestsuitable equipment to minimize soil compaction and root-breakage. Scarred portions of trees and root injuries, especiallyduring hot, dry weather, attract Ips
and black turpentine beetles.
W ounds invite infestation.
Τηε φολλοωινγ πραχτιχεσ αρε ρεχοµµενδεδ ωηεν πλαντινγανδ µαινταινινγ πινε στανδσ:
Use the pine species and spacing intervals best suited to the area
If necessary, thin stands to maintain vigorous and healthy
Promptly salvage or destroy potential Ips
breeding material, such
as pines that are severely damaged by wind, lightning, fire,disease, insects, or other destructive agents.
In residential areas, maintain shade tree vigor by watering duringperiods of drought.
Several insect parasites and predators, as well
as fungus diseases, provide some natural control of Ips
populations. Woodpeckers sometimes remove Ips
from the bark,
especially during the winter when beetle development is very
Natural disasters such as prolonged droughts, hot
wildfires, or severe windstorms sometimes result in large Ips
infestations despite good preventive forest management.
Logging of beetle-infested and recently killed trees through
timber sales is often an effective way to reduce bark beetle
populations and minimize further timber losses.
Chemical control of Ips
infestations under forest conditions isseldom warranted. If chemical control is necessary to protecthigh-value trees in residential or recreational areas, the nearestCounty Agricultural Extension Agent, State AgriculturalExperiment Station, or USDA Forest Service office should becontacted in order to obtain current chemical controlrecommendations.
Other control methods are burning, chipping, debarking, orburying infested portions of trees. Burning should be restrictedto periods of low fire danger, and Federal and State laws shouldbe observed.
Timber Managem ent Practices:
Timber owners may consult
their nearest county, State, or Federal forestry personnel for
recommendations on tree species selection, spacing, thinning,
salvage logging, or other management practices to be followed in
a particular stand or area.
Baker, W. L. Eastern forest insects. Misc. Pub. 1175.
W ashington, DC: U.S. Department of Agriculture, ForestService; 1972: 259-262.
Belanger, R. P. Silvicultural guidelines for reducing losses to thesouthern pine beetle; In: Thatcher, R. C.
et al., ed. The southernpine beetle. Tech. Bull. 1631. Washington, DC: U.S. Departmentof Agriculture, Forest Service, Science and EducationAdministration; 1981: 165177.
Hopping, G. R. North American species in group IX of Ips
DeGeer (Coleoptera: Scolytidae). Can. Entomol. 97: 422-434;1965.
Lanier, G. N. Biosystematics of the genus Ips
(Coleoptera:Scolytidae) in North America. Hopping's groups IV and X. Can.
Entomol. 104: 361-388; 1972.
Thatcher, R. C. Bark beetles affecting southern pines: a reviewof current knowledge. Occas. Pap. 180. New Orleans, LA: U.S.
Department of Agriculture, Forest Service, Southern ForestExperiment Station; 1960, 25 p.
W ilkinson, R. C.; Foltz, J. L. A selected bibliography (1959-1979) of three southeastern species of Ips
engraver beetles. Bull.
Entomol. Soc. Am, 26: 375-380; 1980.
W ood, D. D.; Stark, R. W. The life history of Ips calligraphus
(Coleoptera; Scolytidae) with notes on its biology in California. Can.
Entomol. 100: 145-151; 1968.
Managing Bark Beetle Infestation with Blue Stain Fungus
First, the bark beetle species in our region are only capable of colonizingextremely stressed trees, so, foremost, bark beetles are a plant healthproblem. Many believe that infested pines are so stressed that theywould die even if bark beetles did not finish them off. However, Ibelieve that this is not the case, that if stressed trees can be protectedfrom bark beetles, they could survive, if the ultimate source of stress canbe relieved. We are currently testing this hypothesis experimentally inthe case of red pine, drought stress, and bark beetles.
Second, in my experience, when bark beetles attack, in most cases it is inoverwhelming numbers due to mass attack behavior mediated by theaggregation pheromone they produce. Such a great proportion of phloemis destroyed that the tree is badly girdled and would succumb even ifblue stain fungi did not clog the phloem. This means it is necessary toprotect the tree from bark beetles, as well as associated fungi[Ceratocystis ips
(Rumbold) C. Moreau]. Treating with a fungicidealone would not be effective (even assuming the fungicide was effectiveagainst blue stain), if the tree were not also protected from the beetles. Inour tests, we have found imidacloprid (Merit, Bayer Advanced Tree andShrub Insect Control) to be effective, but my recommendation isprotective bark sprays with Astro [permethrin], which we have found tobe very effective against Ips pini, the main bark beetle in the Great Lakesstates.
Finally, blue stain fungus [Ceratocystis ips
(Rumbold) C. Moreau ] is notuniversally present in bark beetle infested trees, and interesting newresearch is showing that blue stain fungus is not mutualistic, as it hasbeen assumed, but is actually antagonistic, competing with bark beetlesfor phloem resources. Studies are showing that bark beetle performanceand survival are decreased in the presence of bluestain fungus (whichhitchhikes in external cavities of the bark beetle, rather than in the gut
My bottom line recommendation is to protect stressed pines with Astrobark sprays, and work to alleviate the source of stress if possible.
Drought stress is big factor, and there was an increase in bark beetleproblems towards the end of last summer, which means there will behigh populations this April when over wintering adults become active.
However, many pines (which do not occur naturally in most of Ohio) areinherently stressed because they are planted in soils to which they arepoorly adapted. This is a more difficult challenge to manage.
Dan HermsDepartment of EntomologyOhio State University / OARDC1680 Madison Avenue W ooster, OH 44691phone: (330) 202-3506fax: (330) 263-3686ema
NOTES & FOLLOW- UP ACTIONS
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