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Western Spruce Budworm Aerial Treatment Plan

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closeup of a bud worm crawling among pine needles on a tree branch.The Pikes Peak Region is currently experiencing a chronic infestation of Western Spruce Budworm (WSBW). This is causing thousands of trees to become partially defoliated, or have the needles eaten down to the branch or twig. These trees are reddish to brown and “look dead", although many may not be.

A recent survey of fir trees in the canyon indicated 78% are infested with Western Spruce Budworm. Given the many natural resources in this area, it is critically important to control the infestation in order to

  • protect the live green canopy of the trees,
  • reduce defoliation and death of the forest,
  • protect water quality and quantity, and
  • protect the area from long term fire hazards.

The City of Colorado Springs Forestry Division and area partners will be implementing an aerial treatment plan (tentatively) the week of June 5, 2017.

Stay up-to-date on the project

closeup of a bud worm crawling on a pine cone being held in someone's hand.To receive updates about the Western Spruce Budworm Aerial Treatment days, please send your email address to

  • Residents who add their names to the email blast list will receive notice of imminent spray activity with as much forewarning as possible
  • Spray applications are targeted for forested areas only and will not be applied directly over homes

  • FAA regulations require flight operations to ovoid residential areas wherever possible

  • It is suggested that residents and their pets stay inside while the helicopter is spraying nearby but not required

  • Residents may return to their normal activities immediately after application

  • Residents are encouraged to monitor the web site for updates on day to day operations as spraying applications are very dependent on good weather and tend to be extremely fluid

Treatment Area

The City of Colorado Springs will be spraying two treatment areas on City property:

  • Blodgett Peak Open Space
  • North Cheyenne Cañon Park​

Other private property owners are also participating in the treatment area, including The Broadmoor and Seven Falls, Broadmoor Resort Community, Cheyenne Mountain Propagation Farm, Cheyenne Mountain Zoo and the El Pomar Foundation. (Treatment funded by each individual property owner.)

Treatment Blocks 

  • PDF map of closure areas (including road closures)
  • PDF map of treatment areas by polygon
  • Treatment areas by block (All dates are tentative. Spray protocols must be within certain weather parameters and spray block sequences may change on very short notice.)
    • Block One: The Zoo, BRC, Propagation Farm, The Shrine (Completed on June 5)
    • Block Two: North Cheyenne Canyon & Blodgett Peak Open Space (Completed on June 6)
      • North Cheyenne Cañon and Stratton Open Space - closed all day Tuesday, June 6. UPDATE: Crews are finishing up work early. These areas will open at 11:30am on 6/6.

      • Blodgett Peak Open Space - closed for approximately 30 minutes during the early morning of June 6.
    • Block Three: Seven Falls, Zip Line Polygons, North Cheyenne Canyon West Units, Seven Falls interior (completed June 7)
    • Block Four: Seven Falls Soaring Adventures (zip lines), Old Stage Road Corridor (then interior) (Completed June 8)
    • Block Five: Cloud Camp and access road then interior, Broadmoor South Units (Completed June 8)

View exactly what areas have been sprayed

Spray protocols must be within certain weather parameters and spray block sequences may change on very short notice. Treatment is tentatively scheduled to start June 5. Once the treatment starts, this section will be updated every day to show you exactly what areas have been sprayed.

Q & A

What is the Western Spruce Budworm Infestation?

  • Why does there appear to be so many dead trees near Cheyenne Mountain and in North Cheyenne Cañon Park?

    White fir and Douglas-fir trees in North Cheyenne Cañon west of Colorado Springs are currently experiencing chronic defoliation and bud damage from the western spruce budworm. Following epidemic population growth in 2015 and ’16, the Mount Cutler Trail corridor is the most heavily affected and exhibits severe defoliation including damage from another defoliating insect, the Douglas-fir tussock moth. Canopy loss caused by these pests can be severe following repeated infestations and highly visible; thousands of grey, completely dead trees can be expected to be seen by park users. Current infestations will exhibit a reddish tinge throughout the overall canopy where newly active larvae begin feeding on new buds and needles.

    Western spruce budworms overwinter as larvae in silken cocoons and begin feeding on buds and second year needles in late May. As the new needles and buds are consumed, they turn red then orange giving the forest canopy a reddish hue. Adjacent shoots are webbed together and may appear distorted or stunted. Larvae develop through 6 stages and grow from nearly invisible to just over 1 inch in length. Late stage larvae have tan to chestnut-brown heads with olive-green to white bodies. They pupate in June and emerge as adult moths in July to early August.

    A recent survey of fir trees in the canyon indicated 78% are infested with western spruce budworm. Tussock moth, although epidemic for the last two years, has predictably disappeared, it’s cyclical and flashy history held true. Typically, WSBW does not warrant treatment; its nature being more chronic than epidemic. However, given that the watershed where the infestation is occurring has multiple owners and resource values, City Forestry, a division of Colorado Springs Parks and Recreation, along with Colorado State Forest Service, Colorado Springs Utilities, the Broadmoor, and others are in the initial stages of planning an aerial spraying treatment for the week of June 5, 2017. The control of the infestation is critical to protecting the live green canopy of the trees, reducing defoliation and death of the forest, protecting water quality and quantity and protecting from long term fire hazards.

Pictures of Tussock Moths, Western Spruce Budworms, and Damage

Douglas-fir Tussock Moth Fact Sheet

Western Spruce Budworm Fact Sheet

What is the City doing about the infestation?

  • What is the City’s plan? City Forestry is in the planning stages for a large scale aerial treatment spraying scheduled for early June 2017. The City will hire a contractor who will use helicopters designed much like crop dusters and capable of flying low level missions, to apply a biological control pesticide treatment.
  • Why wasn’t anything done before the infestation reached “epidemic levels”? City Forestry and both the US and Colorado State Forest Service have been aware of the infestation and have been actively monitoring it for the past several years. Aerial surveys of the area south of Cheyenne Mountain and NORAD the last two years indicated the moths’ presence; however the size of the infestation did not warrant an active response. In addition, DFTM populations are typically fleeting; here today and gone tomorrow, rarely reaching epidemic levels along the Front Range.
  • I don't see any dead trees in Blodgett Peak Open Space. Why is the City spraying this area? The Western Spruce Budworm​ are present in these areas and the treatment is being performed as preventative measure to stop the spread of the infestation and protect the forest health.​
  • Is this treatment really needed? What are the benefits? The current infestation that we plan to treat is approximately 3,000 acres. Doing nothing may allow the infestation to grow in size and completely defoliate (and kill) all the trees within that area. The treatment is intended to protect soil and water quality, wildlife habitat, aesthetic quality, recreational opportunities and visitor experience. It is also intended to protect a portion of the Pikes Peak watershed in this area, which provides about 15% of the City’s drinking water.
  • Who are some of the other stakeholders and landowners involved in this project? The City of Colorado Springs, Parks, Recreation and Cultural Services; City Forestry; The Broadmoor Hotel; Seven Falls; Cheyenne Mountain Zoo; El Paso County Parks; Colorado Springs Utilities; Friends of Cheyenne Cañon, Palmer Land Trust, US Fish and Wildlife and other entities are all in support of this important insect control treatment.
  • What other agencies are involved in addressing and minimizing environmental or other impacts? The City of Colorado Springs is consulting with and abiding by all regulations concerning the use of biological pesticides of the following agencies: Colorado Department of Public Health and Environment, El Paso County Division of Public Health and Environment, Colorado Parks and Wildlife, US Fish & Wildlife, and Colorado Department of Agriculture.
  • How is the project being funded? Funding for each individual property is being supplied by the property owner. ​The City’s General Fund is covering the costs of spraying the portion of the treatment area on City property: North Cheyenne Cañon Park, and Blodgett Peak.

​What treatment is being used?

  • What is the treatment that will be sprayed? A biological control pesticide called Bacillus thuringiensis var Kurstaki, or BtK, will be used. BtK has been used for over 65 years in the forest industry. It is considered the biological agent of choice in the majority of forest protection programs in North America because it is considered ecologically friendly and effective.* The specific BtK product that will be used is called Foray48B.
  • Why are you using a biological control instead of a chemical pesticide? Aerial application of a chemical pesticide would pose a risk to our community’s water supplies and secondary impacts to humans, fish, wildlife, birds and beneficial insects. Also, chemical pesticides immediately kill any insect they come in contact with, including many beneficial ones. BtK is organic, and highly specific to the insects that it acts upon, namely lepidoptera or butterflies and moths. It is virtually harmless when coming in contact with any other insect other than lepidoptera species. It must be ingested by the larvae to become active and it takes about 5-7 days to cause death. When eaten, these natural proteins are toxic to certain insects, but not to human beings, birds, or other animals. Additionally, BtK is quickly biodegraded in nature, unlike chemical pesticides that form by-products and residues of environmental concern. BtK has been used extensively in commercial urban and rural forest pest management for over 30 years. A solid record of safety and health has been amassed over this time.*
  • How Effective is BtK? BtK effectiveness is comparable to chemical applications in controlling many pest insects when pest population densities are low to moderate. BtK is less likely to be as effective as chemicals when pest populations are extremely high unless multiple applications are conducted. However, a control strategy does not have to kill all the target insects in order to be successful. In fact, studies indicate that there are benefits to maintaining some pest insects in an area to support the population of natural enemies. Because it can take several days for BtK to kill larvae, there is not an immediate reduction in the pest population as is the case when some chemical insecticides are used. BtK is effective, but takes a little longer to see the results.*

Is BtK/Foray harmful? What are the impacts?

  • Is Foray harmful to humans? BtK is a common bacterium found in soils throughout the world. People are repeatedly exposed to BtK and many other microbes every day. Because BtK naturally persists in soil and is also sprayed on many crops (including those that are organically grown), it is likely that you are exposed to BtK during the course of your daily life. If you eat fruits and vegetables, you have probably already ingested BtK, likely without any ill effects. It has minimal environmental impact and it will not harm other types of insects, fish, birds or mammals. As required by the United States Environmental Protection Agency, extensive, oral and intravenous animal studies have been conducted with Foray. No toxic effects were seen when significant quantities of BtK were fed or inhaled. Very mild, temporary skin irritation and moderate, temporary eye irritation was observed in the tests when it was applied directly to the skin and into the eyes. These effects were totally reversible.*
  • What else is in Foray besides BtK? Will These Other Ingredients Harm the Environment? Foray is a biological insecticide which contains spores and crystal-shaped proteins produced by the naturally occurring bacterium Bacillus thuringiensis variety kurstaki, or BtK. Foray is a very selective insecticide and is not designed to control a wide variety of insect species. All Bt products are produced in a similar fashion. The BtK is grown in large enclosed fermentation tanks. Foray is produced using ingredients and a technology which is similar to those used to make beer or spirits. During fermentation, the bacteria (BtK) reproduce in a pre-sterilized growth medium containing basic food sources, such as corn, potatoes, grains, etc. After the fermentation is complete and the bacteria are grown, the fermentation material, including the BtK, is collected. This material becomes the basic ingredient of Foray. This basic ingredient is composed of the BtK, which is the active ingredient, and the residual fermentation growth material and water. The water and residual fermentation growth material are referred to as “inserts” or inactive, because they are not “active” against insects. Several other inerts are added to this fermentation material, BtK and water, to make up the final formulation of Foray. These other ingredients comprise a small proportion of the total formulation. In fact, nearly 90% of Foray 48B for example is composed of water, the residual fermentation growth material, and the BtK, (and one other inert which is a food-approved carbohydrate). The other inactive or inert ingredients are added to maintain the quality of the BtK formulation, to make it easier to handle, and to protect the activity of the BtK. Some of these ingredients help ensure the microbial quality of Foray by acting to control the level of possible contaminating natural microorganisms. These ingredients, added in very minor amounts to control contaminating bacteria and molds, are also used in many foods in Canada and the U.S. for the same purpose. All inert ingredients in Foray formulations are included in 40 CFR 180.1001. This list has been designated by the EPA as “exempt from the requirements of a residue tolerance on raw agricultural commodities”. VBC verifies that none of its BtK formulations contain toxic inert ingredients, such as benzene, xylene, or formaldehyde. Additionally, and of considerable importance, not just the BtK powder itself, but our final end-use formulations are tested toxicologically. In this process the safety of both the active ingredient and inerts are assessed and quantified.*
  • What effect will BtK have on people with immunodeficiency, asthma or allergies? Exposure to a BtK spray program is not likely to result in the development of new allergies, asthma or other hypersensitive reactions. Individuals with pre-existing allergies, asthma or hypersensitive individuals, especially those sensitive to normal exposure to soil or smoke and pollutants, could feel some temporary effect. The exposure level to BtK from an aerial spray program is very low in comparison to the levels applied in safety and health related testing. Even at higher levels used in tests, BtK has been shown to be safe. Individuals with any of the particular medical conditions described above should consider seeking the advice of their physician.*
  • Is Foray harmful to non-target animals, birds and beneficial insects? The BtK in Foray has been tested against mammals, birds and other insects. In all cases, when Foray was tested at doses far in excess of the levels to which these organisms would be exposed during a routine tree spray program, no harmful effects were observed.*
  • Will BtK injure plants? BtK has been sprayed on millions of acres of trees and other plants. There have been no reports of any plant damage. BtK and similar products are commonly used on market gardens and in greenhouses.*
  • Is Foray harmful to aquatic organisms? Foray has shown no adverse effects in aquatic environments. BtK has been tested against freshwater fish and aquatic invertebrate. After extended exposure tests, there were no adverse effects observed.*
  • How can we prove that BtK is not a harmful product? BtK meets the safety standards set in the USA, Canada and in all other countries. In the United States, commercially available products are reviewed and certified for use by the Environmental Protection Agency. All pesticide applications must comply with local, state/provincial, and federal regulations. In addition, researchers continue to monitor programs for potential impacts. While it cannot be proven that any product is absolutely safe, it can be demonstrated that when BtK is applied following the label instructions that the risk to non-target organisms, whether they are birds or humans, is acceptably low.*
  • Will Foray cause damage to car finishes? ​There is nothing in Foray that will cause damage to automobile finishes. These products are formulated to stick to the surface of leaves when they dry. Therefore, it is easiest to remove from any surface while it is still wet. To remove dried Foray from any surface, simply soak the dried droplets with water and then sponge or wipe with a soft cloth. A cleaning product normally labeled for car washing may be needed if the dried spray has been on the surface for a while. The sooner the surface is cleaned, the easier it will be to remove the spray droplets. If the automobile’s paint is old, oxidized, and/or severely weathered, Foray will adhere to this porous surface; it will be more difficult to remove. A large bath towel may be soaked and placed upon the painted surfaces for several minutes to allow the Foray deposits to become rehydrated. This will make the spray deposit easier to remove. In extreme cases, several soakings with a wet towel may be required.*

*Excerpts from Protecting our Forests - Protecting our Future (Foray Technical Manual)

What is the City doing to mitigate any potential impacts to humans, wildlife and the environment?

  • Will the City do anything to notify individuals who are sensitive to pesticides? Residents whose property abuts the treatment area may register with the Colorado Department of Agriculture as a pesticide-sensitive person and will be notified prior to treatment. Register here. Please be advised that the registration process takes more than a week.
  • Will there be any park or trail closures? Initially yes. While BtK has a proven track record to be harmless to all but a very narrow range of insects, it is recommended that the spray area access be restricted until the application is complete.
  • How will you protect Colorado's Outstanding Waters within the spray area and endangered species like the Greenback Cutthroat Trout found in these waters? There are three designated Outstanding Waters in the spray area: Bear Creek, North Cheyenne Creek and South Cheyenne Creek. Although Foray has shown no adverse effects in aquatic environments, the City is taking precautions in respect for the aquatic life and the Colorado Clean Water Act. City Forestry has been in consultation with aquatic biologists from Colorado Parks and Wildlife, the US Forest Service and US Fish and Wildlife. There will be a 50 to 200 foot no spray zone (drainage buffer) along North Cheyenne Creek and South Cheyenne Creek. As a result of conversations with the US Fish and Wildlife Service and the US Forest Service and their concern with regard to the endangered species of Greenback Cutthroat Trout, City Forestry will not pursue aerial treatment of the infestation in the Bear Creek watershed. Extenuating factors include but are not limited to:
    • Low level infestations of both defoliating moths in the Bear Creek watershed (including Jones Park) do not warrant the risk of disturbing fish habitat with any material that may interrupt the food chain or change water quality

    • Extremely low level Greenback cutthroat trout populations that literally constitute the last of that species anywhere in the world
    • Protections placed upon the fish under the Endangered Species Act that clearly define conservation measures
    • Text from the “Bear Creek Watershed Assessment”, a USDA / USFS document, dated 2013, further describe these concerns:

      “At present, the sole known remaining population of genetically pure greenback cutthroat trout inhabits Bear Creek. The greenback cutthroat trout is currently listed as threatened under the ESA. Greenback cutthroat trout are also considered an aquatic Management Indicator Species (MIS) for the PSICC. The population occupies about 4.1 miles of Bear Creek of which 3.4 miles are considered fully occupied and the remaining stream is considered transitional habitat. No other fish species are present in the watershed.”

    • Colorado's Outstanding Waters within the spray zone (map)
    • There is a threatened butterfly in Colorado, the Pawnee Skipper. Won't BtK/Foray threaten this species of insect? While BtK/Foray does act upon very specific insects, namely lepidoptera or butterflies and moths, the Pawnee Skipper habitat does not lie within the treatment spray zone. (See map.)

Exactly when and where will the aerial treatment spraying take place?

  • When will the spraying take place? The aerial spraying is scheduled for early June 2017. At that time the moths will be in the larval stage and most vulnerable to treatments.
  • How will I know what days the spraying will occur? There will be multiple public service announcements aired on local TV and radio news stations, print media and on the web. The City’s communications office will also contact the appropriate open space Friends groups and post the announcement through social media. Signage will be placed at major trailheads to alert park and trail users. To receive updates about the Western Spruce Budworm Aerial Treatment days, please send your email address to ​
  • Where exactly will the spraying take place? - see "Treatment Blocks" section above.
  • Map of Treatment Areas - see "Treatment Blocks" section above.

How will forest health be impacted?

  • Will the trees come back? If completely defoliated, or if more than 50% partially defoliated multiple years in a row, no. Many trees that were only partially defoliated may have enough stored reserves in the roots to replace missing needles with emergency response needles that can re-foliate the tree. Many trees will survive, although they may appear depleted for many years.
  • Will there be fire danger because of the dead trees (if they are dead…)? Yes, until the dead needles fall off. Once the needles fall off, the crown fire potential may actually go down. A lowered crown fire potential will be replaced by a different fire suppression issue: a lot of heavy fuels that will make extinguishment difficult.​

What do I do about Western Spruce Budworm on my property?

  • I found Western Spruce Budworm caterpillars climbing on my tree; should I spray? City Forestry recommends contacting a reputable ISA certified contractor to diagnose the severity of the problem. Western spruce budworm are always present in the forest at endemic levels and may not necessarily warrant spraying.

View a list of all licensed tree services in the City of Colorado Springs.

2016 Letters of Support

Sources & Reference Materials

Questions? City Forestry Division: 719-385-5942