Change in vegetation over time is integral to all forest ecosystems and the creatures that live within them. Unfortunately, this concept often clashes with the human need for stability in a fast changing world. However, many insects and diseases are integral to creating healthy and diverse patterns of vegetation over the landscape even though they sometimes kill or stunt large patches of trees.

For instance, insects and disease organisms help decompose and recycle nutrients, build soil, maintain a diversity of tree and other plants, as well as generate snags (standing dead trees) and down logs needed by many different species of fish and wildlife. In fact, many species of wildlife depend upon insects and disease organisms to create habitat or provide food.
The winners per se in the current mountain pine beetle epidemic are species such as the brilliantly colored western tanager, mountain bluebird, olive-sided flycatcher, nuthatches, chickadees, and woodpeckers.
All of these bird species benefit from actually feeding on the adult beetle or their larvae, as well as the increased amount of dead trees available for the excavation of summer nest holes, and warm winter roosts. The olive-sided flycatcher is particularly dependent on open areas of recent forest disturbance that have several snags from which they can perch to locate and capture flying insects.
Species such as the northern flicker are attracted to beetle killed stands of trees for the abundant food and available snags in which to excavate their nest cavity. Snags take many years to develop into suitable homes for cavity nesters.
Large-diameter snags left standing from this epidemic may house beetle-eating birds next epidemic. Eventually other bird species and wildlife such as nuthatches, chickadees, small woodpeckers, squirrels, etc., build their nests in abandoned flicker holes.
Many species of animals such as juncos, white-crowned sparrows, elk, mule deer, and the snowshoe hare benefit in areas where the beetles have killed 50-75% of the canopy trees. When the beetles kill this many trees the canopy is opened up allowing sunlight to reach the ground, while at the same time nutrients that were locked up in the living trees are now available to grass and shrubs.
Juncos and chipping sparrows are both ground nesting birds that benefit from the increased ground cover. In addition, birds like the sharp-shinned hawk, while dependent on dense tree cover for its own nest, benefits from the increase in juncos and white-crowned sparrows, which in Colorado have been recorded as two of their most frequent prey items.
Open areas of beetle-killed trees do not meet the thermal requirements of elk and deer but do provide areas of high quality forage. Similarly, snowshoe hares, voles, and deer mice benefit from the denser ground cover both for increased forage and hiding cover. An increase in small mammals, or prey in turn benefits their larger predators such as bobcat, lynx, and marten.
Unfortunately, some species of wildlife such as yellow-rumped warblers, pine grosbeaks, northern goshawks, and red and Abert's squirrels depend on denser canopy cover and do not benefit from large areas of beetle-killed trees.
The diversity of tree species mixed in with ponderosa pine will hopefully leave enough large 'green tree' reservoirs to help see these species through until the next generation of pine once again fills in the canopy.
Change is integral to forest ecosystems, without it the many species mentioned would never benefit from beetle or disease infestations. And the species that don't benefit now will once again flourish as the epidemic subsides and a new generation of pines takes its place.

Q & A

Is it ok to leave a dead tree standing?

Yes, leaving a dead tree standing can be beneficial to wildlife.
Dead trees can provide forage habitat for insect eating species, perching opportunities for birds, and homes for cavity creatures.

Pine Beetle Control in Mesa Antero A Homeowners Point of View

Mesa Antero is a private subdivision located six miles south of Nathrop. The subdivision, comprising some 1,200 acres divided into 273 lots varying in size from 2 to 13 acres, is bounded on its west side by land of the San Isabel National Forest. About half of the lots have residences constructed on them. The vast majority of the lots have some tree cover, ranging from dense stands of ponderosa pine on the western two-thirds of the subdivision to predominantly pinon pine on the eastern portion.

Mesa Antero acted early and aggressively to control the spread of the mountain pine beetle infestation on its land. When beetle-infested ponderosa were first observed in the fall of 1996, the property owners association was instrumental in organizing a group of some thirty volunteers who, after a training workshop conducted by the Colorado State Forest Service, proceeded to inspect all of Mesa Antero for evidence of pine beetle infestation.
The volunteers flagged suspect trees, but a second opinion on those suspect trees was rendered by a professional forester from the Colorado State Forest Service.
Infested live trees were cut down and removed from the area, since once a tree has been successfully attacked; there is no way to save that particular tree. Removal of the infested tree insures that its beetles are not available to infest additional trees in the subsequent yearly beetle cycle.
This cooperative effort between the Colorado State Forest Service and volunteer inspection teams made up from Mesa Antero's private landowners has continued in its original form for four years now.
Although the number of beetle infested trees identified and removed has increased in these four years (17 in 1996, 65 in 1997, 98 in 1998, and 105 in 1999), the toll of ponderosa pine lost would undoubtedly have been much higher if control measures had not been undertaken.
Unfortunately, the National Forest land on the west and northwest border of Mesa Antero contains many clusters of beetle-infested pines. These sites of active infestation are an ongoing threat to the federal land as well as to the nearby private lands.
As an additional protective measure, Mesa Antero has encouraged its landowners to contract with a commercial service to spray some of their ponderosa pines (1,000 trees in 1999) with the product Carbaryl (Sevin is one trade name). This preventative spraying, which has to be done each year, is effective in protecting ponderosa pines from attack by the pine beetle. However, because of the expense involved, such spraying is practical for only a limited number of "must save" trees.
Cooperation between private landowners with adjoining properties, and early action while the number of infested tree is small is the key to an effective beetle control program.
Removal of newly infested trees by an individual property owner is of limited benefit if the surrounding neighbors are not doing likewise. Pine beetles, as they swarm from a dying host tree to infest nearby green trees, do not respect property boundaries.
Fortunately, Mesa Antero, through an active educational program on the pine beetle epidemic and through the involvement of a large fraction of its resident landowners in the inspection process, has gained the cooperation and support of nearly all its landowners in this ongoing control effort.
Most of Mesa Antero's landowners understand the negative impact that loss of trees from beetle infestation has on aesthetic aspects of the land, on habitat for wildlife, and on property values.

Q & A

How far do MPB fly?

Upon leaving their "childhood" tree, beetles usually only fly as far as required to find another suitable tree to attack.
MPB flights in excess of 5 miles have been documented, but probably involve strong winds. One mile is usually considered a safe distance to segregate infested logs from susceptible trees.

Natural History of the Mountain Pine Beetle

Although it would appear that bark beetles are the mortal enemies of pine trees, a closer look reveals that over the vast spans of time these two organisms have become intimately related and interdependent. While groups of beetles are responsible for killing individual trees, it is important to consider how the populations of trees are affected by the populations of the beetles and vice versa. To get the complete picture it is necessary to look at the relationship of tree and beetle as well as the relationship of forests and beetle populations.
The life cycle of the mountain pine beetle (Dendroctonus ponderosae) is relatively simple, but there are some astonishing surprises. The beetles have a one year life cycle but are evident for only a brief period during the middle of summer. From about mid-July, through August and into September the beetles can be seen flying about on warm, calm afternoons. Both males and females emerge from beneath the bark of a host pine to disperse through the forest, locate a new host, mate and lay eggs.

The Chemical Environment.
By external appearance, the beetles appear to be weak fliers as they bumble their way through the forest. But they are very persistent and in fact are quite directed in their travels. Bark beetles experience a very different world than humans do, their universe is determined by smells, incredibly minute amounts of aromatic chemicals determine their behavior from one moment to the next. Bark beetles use these odors to locate potential host pine trees, and once a host has been located, the beetles release odors to attract more of their kind.
The earliest arriving beetles, to attract others in order to initiate mass attack, produce these chemicals called pheromones. Mass attack is the process by which large numbers of beetles overwhelm a tree's defenses. Pine trees produce large quantities of resin that flows in resin canals, not unlike the way that blood flows in veins. When something damages a pine tree the resin flows to flush out the wound. As they initiate attacks in the host tree the beetles begin to deplete the tree's finite reserve of pine resin. The beetles also have a secret weapon in the form of a fungal ally. When the beetles attack the pine tree they carry spores of a fungus that quickly colonizes the host and helps bring about the death of the tree. These same fungi are responsible for the characteristic blue stain found in beetle-killed trees.

Blue staining is caused by fungi carried by the MPB.

MPB larvae and galleries. Exposed after removal of tree bark.

Life Beneath the Bark.
When enough beetles have initiated attack on a host, the tree's defenses are overwhelmed and the beetles can begin to excavate tunnels (called galleries) beneath the bark in which they produce their young. The male and female mate in the tunnel that is extended vertically underneath the bark. About 50 eggs are laid along the sides of the gallery. The eggs hatch in a few days and small larvae that look like tiny worms begin feeding upon the nutrient rich tissues. The young larvae tunnel away from the main egg gallery and fan out beneath the bark.
The tree that has been attacked remains an apparently healthy green color through the attack period and will remain green through most of the winter. The telltale foliage coloration of a beetle attacked tree will not appear until the following spring when the green foliage turns a lemon yellow which in turn becomes a straw colored orange and finally fades to the red of a dead tree. Despite the green coloration, a successfully attacked tree is for all intents and purposes dead. The beetle larvae beneath the bark and the rapid fungal growth reveal that despite the green color of the foliage, the tree is beyond saving.
As winter approaches the larvae convert the sugars in their food into alcohols in their body. These alcohols, act as an anti-freeze to help the young insects withstand the long cold winter. The beetles are well adapted to the chill of the winter, but occasionally the cold becomes even too much for them and extended periods of extremely cold temperatures can greatly reduce their numbers.
Ecosystem Within the Host.
As temperatures rise with the coming of spring, the beetles resume their activity beneath the bark, feeding upon the inner bark, growing and molting, as they grow larger. By now a large number of other creatures have joined the beetle larvae beneath the bark. A number of natural enemies have entered the galleries to attack and feed upon the beetle larvae. Predatory checker beetles roam the galleries and feed on large numbers of bark beetle larvae. Parasitic wasps search the surface of the bark and lay eggs on bark beetle larvae by using their drill-like ovipoisitor. The wasp hatchling feed upon the bark beetle larva and emerges later to complete the cycle.
In addition to natural enemies, a whole slew of other organisms take advantage of the habitat created by the bark beetle activity. A number of fungi grow in the moist, protected environment and these are grazed upon in turn by tiny mites, fly larvae and the larvae of other beetle species. These associated species are also pursued by predators and several different species of scavenging insects and mites feed upon the by-products of all this activity also pursue these associated species.
The microcosm of life that occurs beneath the bark of the dead tree illustrates once again the immense evolutionary forces associated with the interplay between bark beetles and pine trees. The activity of mountain pine beetles set a complex series of events into action that ends in the complete breakdown of the biomass represented by the living tree.
The beetle larvae pupate in early summer. During this resting stage they transform from the worm-like form they assume as larvae into the familiar beetle shape of adult hood. Pupation is complete by mid-summer and they spend a short amount of time beneath the bark waiting for the proper conditions for emergence. On a warm afternoon in mid to late summer the next generation emerges to complete the life cycle.

Q & A

Will the government come and take care of my trees for me?

The days of massive government direct control programs, where state or federal crews identified, cut and treat large numbers of beetle-infested trees on private land are probably over. However, that does not mean government assistance does not exist, . At this time, help from forestry agencies is limited to technical assistance up to the point of cutting and treating infested trees. CSFS policy is to help in any way we can to assist landowners understand the beetle, make informed decisions, identify infested trees, and get them treated themselves or with contractors.
We will serve as a liaison with the USFS, neighbors, cutting and spraying contractors, and suppliers of treatment materials. Printed material is available from CSFS., USFS, and BLM. CSFS will provide training upon request in all aspects of MPB biology, prevention and treatment. Group instruction will be given preference over individuals, simply because of the sheer number of people making requests. CSFS and private consultants are available to write forest management plans that can provide long term relief from epidemic attacks.
When in doubt about beetles and what is available in the way of help, contact your local office of CSFS.