QUICK GUIDE SERIES FM 2020-6 Piñon

A northwest Colorado landowner points to an adult piñon Ips beetle discovered making a gallery underneath piñon bark. Photo: Dennis Brock, for CSFS

he piñon Ips beetle () is a . As more trees become infested, native Colorado with a notable beetle populations increase, resulting in Tability to take advantage of environmental widespread mortality. changes and spread rapidly. In the Not only can piñon Ips attack southwest part of the state, this insect kills stressed trees, they also can reproduce in more mature piñon pine trees than any any fresh, green, recently cut material over other . 1 inch in diameter, such as green firewood Colorado’s weather patterns help or piles of branches left on the ground create ideal conditions for many bark after pruning or cutting live piñon trees. beetle populations to increase, including Paying attention to how is stored is piñon Ips. Oscillations between warm and of the utmost importance when considering dry spells throughout much of the state beetle life cycles and mitigating risk. have become all too frequent. During Homeowners and landowners can play This Quick Guide periods of below average precipitation a crucial role in minimizing the spread of is produced by the and warmer than average temperatures, piñon Ips by following the tips offered in Colorado State Forest Service trees become stressed from a lack of this Quick Guide. Concentrated outbreaks to promote knowledge transfer. water. Stressed trees have a difficult time can be addressed with a few simple actions defending themselves against beetles and that help keep populations of this insect in succumb to infestations easier than healthy check. t time to : Grea cut an NCY d re A mo RM ve DO p R iñ E on T JAN t IN re e W s DEC FEB .

adults overwinter NOV Piñon Ips 1st gen. Life Cycles MAR adults Piñon Ips beetle. Photo: Pest and Diseases Image Library, bugwood.org Piñon Ips beetles live for eight weeks. OCT In years of drought or warm temperatures, up to four generations can occur in a APR QUICK FACTS season. Adult flight times vary by location, season and latitude. » IDENTIFICATION: Piñon Ips They usually emerge earlier in bark beetles are often light to SEP the southern part of the state 4th gen. MAY dark brown and small, about adults and later in the north. 4 millimeters long. AUG » ACTIVITY BEGINS: once JUNE A . C JULY es daytime temperatures are T e IV tr E ve consistently above 50 SE mo 2nd gen. AS nd adults ON: ut a degrees. If possible, wait to c » ACTIVITY ENDS: once STAGES daytime temperatures are 3rd gen. flying adult consistently below 50 adults (times approximate) degrees. larvae laid to start new generation » Piñon Ips beetles prefer piñon and only rarely attack other pine . They will not attack juniper (cedar) trees.

» Ips is a common group of How Piñon Ips Attack bark beetles that infests pine iñon Ips beetles target piñon , that overwintered underneath the bark. and trees. which typically grow in harsh, low This first generation infests stressed trees, Pelevations below mixed-/ponderosa freshly cut green logs or firewood, or any » There are 11 species of Ips pine forests of Colorado. Piñons often green branches removed after tree cutting beetles in Colorado. Only grow in proximity to juniper trees and (called slash). The smell of fresh piñon sap Ips confusus specializes in lowland shrubs, where conditions are dry attracts the beetles. attacking piñon pines here and precipitation fluctuations are normal. Before piñon Ips die, they mate and and around the southwestern These beetles are attracted to piñon lay eggs to ensure another generation United States. trees with weakened defenses. Piñon will survive. Piñon Ips beetles are prolific Ips usually limit their attacks to trees breeders and can produce up to four » All members of the Ips that are in decline due to root injuries, generations a year. have spines along the ends wounding, compacted soil, winter damage, Once hatched, larvae begin creating of their wing covers (elytra). underwatering or overwatering. However, small galleries in the tree layers under the during high-stress environmental situations, bark (called ), which provide the » Ips beetles rarely attack such as drought, beetle populations can tree with water and nutrients. The larval healthy trees. Most attacks increase and pose a considerable threat, galleries cut off nutrients and water supply occur to newly transplanted even to healthy trees. These beetles kill to the whole tree. This kills the tree by piñon trees by attacking in mass numbers, pines or when trees are slowly starving it to death. and they have to work fast because they During development, larvae increase under stress. only live for about eight weeks. in size. Once they grow into adult beetles » There are 45 species of The trees die when adult beetles create and harden their exoskeleton, they chew Ips beetles worldwide, 31 galleries (tunnels) between the bark and their way out of the bark. These new wood of the trunk and branches, where of those are found in North adult beetles must seek live or recently they mate and lay eggs. America. cut green piñon tree material to survive Piñon Ips beetle flight activity begins in — suitable material that has nutrients to early spring with an emergence of adults sustain larval growth within its phloem.

2 Colorado State Forest Service Quick Guide Series: Piñon Ips Signs and Symptoms of an Infestation

When piñon Ips Pitch tubes attack, needles are a sign throughout the tree has the tree fade tried to drown quickly to a the piñon Ips straw color, beetle with then red and sap as the brown as the insect bores tree dies. into the tree. Photo: Luke Photo: Kamie Dittrich, CSFS Long, CSFS

Fading Needles Pitch Tubes Following a successful beetle attack on a piñon, needles These are a sign the tree’s defense system has attempted fade from green to a straw or rust color. On infested trees, to flush the wound and drown the beetle as it enters the needles continue to die, turning red and eventually brown. bark. Pitch tubes are small, thumbnail-sized clumps of sap By the time a piñon appears to be dying, the beetles that appear on the bark where the beetles attempted to likely have already emerged, moved on and attacked or successfully entered the tree. They have a reddish hue a new tree. In dry years, it is not unusual for needles to from the sawdust the beetles create as they bore through start fading just weeks after infestation. But in years with the bark. Pitch tubes only appear if the tree has enough adequate precipitation, needles may slowly fade for several moisture and energy available to produce sap to defend months after attack. itself during an attack.

Piñon Ips exit Piñon Ips holes, at the top bore through of this section of a tree’s bark, bark, are small creating and concise, like tunnel-like BB holes. galleries The larger hole, underneath. at center, is Photo: Jerald indicative of E. Dewey, USDA Forest activity feeding Service, on larvae bugwood.org underneath the bark. Photo: Kamie Long, CSFS

Entry and Exit Holes Galleries One easy way to tell if a tree is or was infested is to look Another way to diagnose if a tree is infested with piñon for entry and exit holes in the bark. Entry holes can be Ips is by peeling a piece of bark off of the outside of the accompanied by other signs, like pitch tubes and sawdust. tree and looking for galleries in the inner bark (phloem Exit holes are nearly round and the size of a pinhead or BB and cambium). These characteristic tunnels are made by pellet, made when adult beetles emerge from under the Ips adults and larvae underneath the bark, and usually bark. If exit holes are present, even if the tree is still green, form a Y or H shape. Piñon Ips galleries are typically free the beetles have likely emerged and flown to another tree. from boring dust created by their excavation, which sets Ips beetles apart from other bark beetles found in pine species.

3 Colorado State Forest Service csfs.colostate.edu Treatment and Prevention Tips

he best way to prevent Ips beetle your local CSFS forester for information. Currently infested trees are usually still T attacks is to maintain a healthy forest. If dying or recently killed piñon trees green and should be promptly removed. Thinning your forest, by spacing trees are detected, or Ips beetles identified, It is important to remove trees with beetle farther apart and removing those that are all surrounding green trees should be larvae or pupae from the property before unhealthy or have dwarf mistletoe, may inspected to determine if the beetles have they emerge and attack other green piñon help increase individual tree health. Consult successfully attacked other piñons. trees. (See section: How to Handle Wood).

Cutting Trees Winter Watering Spraying » Remove trees infested with piñon Ips » Watering favorite trees in the » Spray favorite trees with a preventive as soon as they are identified. summer in periods of drought and chemical at least two times per year » To prevent colonization, ensure also in winter months can help protect to prevent attack when all material is dry (no green wood against tree stress. beetle populations are high in the area. remaining) or removed from the site » Conifer trees release moisture Environmental and economic before late March. through their needles all year long in concerns around spraying » When bark is cracking and splitting a process called transpiration. When exist, so homeowners must choose from the wood, the tree is dry and the soil is dry from lack of moisture which trees to protect rather than beetles have already left. This wood is (snow or rain), trees can become treating large areas. Chemical safe to move. stressed. treatments should never be applied on piñon trees that provide nuts » Remove dead trees as time and » During the winter, water favorite for human consumption. money allow for hazard trees about once a month when there reduction and aesthetics. This can be is no snow on the ground and the » Treatment options may include done any time of year since there is no temperature is above 40 degrees. In external sprays or injections. Follow sap produced to attract these beetles. some areas, this may only occur in the insecticide labels for application. fall and early spring. Depending on the insecticide, multiple » BETWEEN APRIL AND OCTOBER: treatments per year may be needed. Cutting during this time is not » Apply water at the edge of the tree recommended unless personal safety crown’s drip line, where rain would » Many products on the market drip off. This area is where most of the is a concern. If green material must be contain ingredients necessary to absorbing tree roots are located. The cut when Ips beetles are most active, kill bark beetles. Look at labels for root system of piñon trees includes remove all material from site as quickly active ingredients such as carbaryl, tap and spreading roots, which can as possible (within days) and bury the permethrin or bifenthrin. stump to reduce chances of attracting reach deep and out to twice the beetles. height of the tree. » Use as a drenching spray on the entire trunk and all » IN OCTOBER AND NOVEMBER: As branches greater than 1 inch in daytime temperatures fall below 50 diameter. Follow the manufacturer’s degrees, beetles are unlikely to search recommendation for bark beetle out new material. This is a good time treatment. to split and scatter wood larger than 4 inches in diameter and cut branches into » Once a tree is infested, preventive short pieces, leaving it in sunny locations insecticide treatments are ineffective to encourage rapid drying. That’s and should not be used. Infested trees important because early next spring, should be removed and disposed of beetles may still attack previously cut properly. material that is still green. » BETWEEN NOVEMBER AND FEBRUARY: Winter is the beetle’s inactive period and the best time to cut and remove infested green trees if beetle populations are high. Ensure any slash, chips or wood created is dry prior to beetle emergence in the spring. » Thin forests during winter months to allow for more water, nutrients and sunlight for each tree. Creating more space between trees improves individual tree health and reduces wildfire intensity.

4 Colorado State Forest Service Quick Guide Series: Piñon Ips Is The Wood Still Useable?

Once trees are identified as having a piñon Ips infestation, removing the wood should be done cautiously to avoid spreading the insect further. Cut material left at the base of live trees draws beetles in and allows them to overcome otherwise healthy trees. Move cut material at least 1 mile from any piñons. Photo: Austin Shelby, CSFS

Six Ways to Handle Infested Wood

ood material infested Solar treatments, with or with piñon Ips beetles without clear plastic, are not shouldW be handled cautiously, effective at destroying the as should any previously cut beetles, primarily because of green wood on a property. After their short life cycle. cutting, piñon material may give Wood may be treated in the off a scent that attracts beetles following ways to prevent this for up to six months. insect from spreading:

1. GRIND (MASTICATE) OR CHIP LOGS AND SLASH. This destroys the larvae and quickly dries the slash, making it useless for beetle reproduction. Grinding and chipping should be done ideally in November or December, when beetles are dormant and the material will have time to dry before more beetles emerge the next spring. On larger acreages, professional mastication may be Piñon wood that shows cracking, splitting and chipping an economical method of treatment. bark is dry and safe to use. Photo: Adam Moore, CSFS 2. SPLIT AND SCATTER, DON’T STACK. Wood larger than 4 inches Piñon Ips beetles do not damage the wood in diameter should be split and scattered to encourage rapid inside a tree; it can still be used for lumber, drying before beetle flight resumes in the spring. firewood or other products once it has dried out. If bark is splitting or cracking, the wood is dry 3. TRANSPORT GREEN MATERIAL to a site that is farther than 1 mile from any piñon trees. and safe to use. If exit holes are present on standing dead 4. BURN INFESTED OR GREEN MATERIAL, if burning regulations allow. Take care to remove cut green material from the site, trees, or all the needles have fallen off the tree, instead of piling it, while beetles are active. piñon Ips beetles likely have flown to another tree. Once beetles have left the tree, it can be 5. BURY THE MATERIAL more than 8 inches in the soil. removed any time of year and used for firewood 6. DEBARK LARGE LOGS with chainsaw attachments that assist or other purposes. stripping bark from logs. This exposes beetles to the elements.

5 Colorado State Forest Service csfs.colostate.edu Piñon pines in southwest Colorado show fading, one of the symptoms of a piñon Ips beetle attack. Photo: Dan West, CSFS

Learn More References Acknowledgements about piñon Ips bark beetle Douglas, H.B., Cognato, A.I., Grebennikov, Thank you to the CSFS personnel who and piñon-juniper tree V., and Savard, K., 2019. Dichotomous provided production assistance: management on the CSFS and matrix-based keys to the Ips bark Dan West, Fort Collins state office website at csfs.colostate.edu, beetles of the World (Coleoptera: Katelynn Martinez, Fort Collins state office or contact your local foresters : Scolytinae). Canadian at the nearest Colorado State Journal of Identification, 38: Kamie Long, Grand Junction field office Forest Service field office. 234 pp. Adam Moore, Alamosa field office Furniss, R.L. and Carolin, V.M., 1977. Luke Dittrich, Durango field office Western Forest . Volume 1339. Jodi Rist, Montrose field office Austin Shelby, Montrose field office Luke Cherney, Cañon City field office

The Colorado State Forest Service is a service and outreach agency of the Warner College of Natural Resources at Colorado State University. CSFS programs are available to all without Colorado State University Colorado State University discrimination. No endorsement of 5060 Campus Delivery products or services is intended. 1401 Campus Delivery Fort Collins, CO 80523-1401 Fort Collins, CO 80523-5060 (970) 491-4994 (970) 491-6303 062020.3000 warnercnr.colostate.edu csfs.colostate.edu