Sweeping for leafy spurge biocontrol insects along the Yampa River.

YRLSP's monitoring data is already contributing to a better understanding of the resiliency of the various biological control species in association with differing environmental conditions. This information is invaluable for establishing enhanced biocontrol populations through additional releases in the future.

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To this end, in cooperation with our agency partners and multiple private- landowning stakeholders, in 2019 the YRLSP began an accelerated leafy spurge biological control release program. The goal is to distribute Aphthona (flea beetles) and Oberea (stem-boring beetles) in appropriate locations throughout the full extent of the riparian habitats of the Yampa Basin, from Hayden to Dinosaur National Monument. Each new YRLSP release site will be subject to continued biological control monitoring in the future.

Currently leafy spurge biological control insects are available to us (in seasonally variable quantities) from collections made by the Colorado Department of Agriculture (CDA) at various Colorado Front Range locations, or from a vendor collecting in Montana. However, ultimately the YRLSP hopes to establish a number of viable local nursery sites for its own Yampa-Basin-sourced beetle collection and redistribution. 

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2019

In the first year of the YRLSP biological control release program, approximately 7,300 flea beetles collected by the CDA on the Front Range (and donated to the YRLSP) were released on or in the vicinity of the Yampa River State Wildlife Area (YRSWA).

2020

In June 2020, four YRLSP volunteers upped the ante by traveling to the Front Range to aid the CDA in their annual collection of leafy spurge biological control beetles. Under the tutelage of the CDA's John Kaltenbach, on the first day approximately 27,000 flea beetles were collected from the former Lowry Bombing and Gunnery Range east of Denver. Day two was then spent at the CDA facility in Broomfield, sorting the flea beetles from stray plant parts and the rest of the insect "bi-catch," before packaging them into 1000-insect lots for distribution by the CDA across Colorado. In return for our contributions, the YRLSP's share of the take was thirteen 1000-insect lots of Aphthona, and one lot of Oberea (Oberea is typically released in lots of only 100 insects).

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Upon our return to the Yampa Yalley, two additional days were spent releasing the biological control insects at thirteen separate locations in Routt and Moffat counties. In June, Routt County Weed Program released 500 Aphthona northwest of Hayden. Then, in July 2020, YRLSP volunteers also helped release an additional 10,000 flea beetles on the Yampa River State Wildlife Area, purchased by the YRSWA from a vendor in Montana.

This brought the total for just the 2020 biological control releases alone in the Yampa Valley to approximately 23,600 insects—roughly a third as many again as recorded during the entire "legacy release" period of 1989–2017!

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2021

The YRLSP was looking forward to another successful volunteer collection trip to the former Lowry Bombing and Gunnery Range in 2021, but (despite the extreme drought conditions prevailing on the Western Slope) continuously cool, wet spring conditions on the Front Range resulted in poor collection numbers during test runs by CDA crews. Ultimately it became clear that a collection trip to the Front Range by YRLSP volunteers would have produced only limited returns.

Nevertheless, John Kaltenbach of the CDA was able to supply us with 3,000 Aphthona and 250 Oberea, while Tyler Jacox of Colorado Parks and Wildlife (CPW) was able to acquire an additional 6000 Aphthona and 200 Oberea from the Montana vendor. All of these insects were released at new locations in the Yampa River State Wildlife Areas and Moffat County. The Routt County Weed

Program also released another 1000 Aphthona northwest of Hayden.

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2022

The YRLSP again traveled to the former Lowry Bombing and Gunnery Range in June of 2022, for another successful volunteer collection trip under the auspices of the Colorado Department of Agriculture. This time we brought home approximately 12,000 Aphthona and 200 Oberea, which were quickly released at sites in Moffat County. Another 2000 Aphthona from the Lowry collection were later released by John Kaltenbach in the Yampa River State Wildlife Area, during our two-day Youth Outreach event. 

Tyler Jacox of the CPW was again able to procure an additional 6000 Aphthona and 300 Oberea from the Montana vendor, all of which were also released in the Yampa River State Wildlife Area. A last-minute, surprise gift of an additional 4000 Aphthona were also added to the new releases on the YRSWA. (Originally intended for release in the White River basin, these were donated to the YRLSP by Deirdre Macnab of the White River Alliance, after they were mistakenly delivered to an address in Steamboat. With the clock ticking, and no one with the White River Alliance readily available to pick them up, Deirdre turned to the YRLSP for help rescuing the beetles.) 

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The YRLSP also purchased an additional 6000 Aphthona and 200 Oberea from our Montana source, which were released at five sites in Moffat County. Finally, the Routt County Weed Program also released an additional 1000 Aphthona on private lands south of the YRSWA.

Overall, in 2022 a total of 18,400 biological control insects were released in Moffat County, and another 13,300 in Routt County, for a combined total of approximately 31,700 biocontrol beetles for the season.