Biocontrols are host-specific insects or pathogens that can be used to control noxious weeds. They are introduced from the target species’ native range after years of rigorous testing to ensure that they will not damage native plant species.
In Colorado, biocontrol agents are reared and distributed from the Palisade Insectary.
Biocontrols reduce the competitive edge of noxious weed species, though they will never truly eradicate a population, which helps the native plants flourish. Many people are intrigued and interested in using biocontrols as it seems like a silver bullet: a passive, natural method for managing weeds while reducing the use of herbicides. However, biocontrols have their limitations and are not suited for every property.
First off, the size of the infestation needs to be large enough for the biocontrols to have a sustaining population. A quarter acre or smaller parcel is not a great candidate for biocontrols as they will likely leave the area in search of a better food source or move over to a neighboring property where the weeds may be managed by mowing, herbicide, hand pulling, etc., which disrupts their life cycle. If several neighbors on smaller acreage want to use biocontrols together, this is a great option, though joint management may become a problem when one property sells and the new owner has a different vision of weed management.
If a plant is poisonous to livestock and is growing in a pasture or hay meadow, then chemical or manual control of the plant is a better idea to prevent accidental ingestion.
Species on the Colorado Noxious Weed A List can also not be managed with biocontrols as their eradication is legally mandated. The only current A List species in Archuleta County are myrtle and cypress spurge, and no biocontrol agents have been approved to manage those species.
Biocontrols work best on large populations that are in tricky locations such as hillsides, steep gullies and the like. They can also be released on species that the management goal is suppression or containment.
The reality of invasive species is that we won’t be able to completely remove them; in some areas, a low percentage of weeds is acceptable management. In scenarios like this, the weed species should be managed along the vector of spread (driveways, property boundary) to prevent their further dispersal.
To request biocontrols, visit the Colorado Department of Agriculture website and click on the “Conservation” tab, “Biocontrol at the Palisade Insectary” and then the “Request-A-Bug” button.
Some biocontrols like the field bindweed gall mites have such high demand that you may have to wait a year (or more) before you receive a shipment.
The Archuleta County Weed and Pest Department does collect some biocontrols locally, which include the field bindweed gall mites, Russian knapweed gall wasps (stingless), musk thistle weevils and Canada thistle rust fungus. Not all biocontrol agents are collected annually.
Archuleta County Weed and Pest is your local resource for managing noxious weed populations and controlling other pests.
75th annual Archuleta County Fair
Get ready for the 75th annual Archuleta County Fair July 30 through Aug. 2 at the Archuleta County Fairgrounds.
Visit archuletacountyfair.com to learn more.
Tickets for the annual 4-H Chuckwagon Dinner are available for purchase from 4-H members July 8-27. Early bird prices are $15 for adults and $5 for kids. Tickets purchased at the gate will go up $5, so get your tickets early.
The 4-H Livestock Auction will follow the Chuckwagon Dinner on Saturday, Aug. 1. Don’t miss out on the fun.
Volunteer for the Archuleta County Fair
Volunteers are needed for the Archuleta County Fair.
Be a part of preserving the rich heritage and timeless tradition of the Archuleta County Fair and help with the 75th anniversary fair in 2026.
You’ll contribute to an annual tradition that brings our community together, supports local agriculture and creates lasting memories for generations to come.
To learn more, contact Tonya Steadmon at tsteadmon@archuletacounty.gov or (970) 264-5931.
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