Montana Biological Weed Control Coordination Project

Montana Biological Weed Control Coordination Project The Project provides leadership, coordination, and education that enables land managers to incorporate biocontrol in their w**d management programs.

Have you ever wondered how many biocontrol agents are in 1 release? It differs quite a bit between species!
08/24/2026

Have you ever wondered how many biocontrol agents are in 1 release? It differs quite a bit between species!

08/19/2026

POV: You are a knapw**d root weevil getting collected, and you're so excited to be released in your new home full of yummy spotted knapw**d with all 99 of your friends!

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The bees would like to tune in on this debate! As 60-80% of flowering plants get pollinated by bees, these little critte...
08/17/2026

The bees would like to tune in on this debate! As 60-80% of flowering plants get pollinated by bees, these little critters play a major role in the success of both native and invasive plants being able to reproduce and expand. Unfortunately, there has been a major decline in pollinators over the last decade - could their food be part of the problem?

Some summer time fun as we're out in the w**ds - how many of these bugs can you find? Picture version on the second page...
08/12/2026

Some summer time fun as we're out in the w**ds - how many of these bugs can you find? Picture version on the second page 🐝🐜🐛 Bonus points if you figure out the hidden categories!

Photos from MTBCP Crew

That's not your friend. Or maybe it is if you're a biocontrol lover like us!Adult moths are about 11mm (1/2 inch) long w...
08/10/2026

That's not your friend. Or maybe it is if you're a biocontrol lover like us!

Adult moths are about 11mm (1/2 inch) long with bright yellow forewings, and dark gray-brown hindwings. Their wingspans can range from 15 to 23 mm (about 3/4 inch). The females are generally larger than the males. They emerge as adults throughout the summer and into early fall while the knapw**d still flowers and buds. They then lay their eggs on the lower parts of the stems and leaves. Once the eggs hatch, they migrate to the root crown where they begin feeding on the plant's roots. The larvae overwinter in the roots and begin to pupate in the surrounding soil in the spring.

The larval feeding on the roots hinders the plant’s ability to uptake necessary nutrients, reducing the biomass and general health of the w**d. With enough feeding on the root of a smaller knapw**d plant, it may kill it entirely. Adult moths do not damage the plants.

Since this agent is a great flyer, it can be found pretty much all over knapw**d patches west of the Continental Divide, and the populations east of the divide are continually increasing.

If you pull up a knapw**d plant and notice a larva in the roots, it’s likely one of two species. Either the knapw**d root weevils or the Knapw**d Moth (Agapeta zoegana). The key to differentiate between the two in their larval state is to notice the shape of the larvae. If it is C-shaped, it is likely a root weevil. If it is straight and slender, then it is likely Agapeta.

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Happy Field Friday! Today we're highlighting just a few of the whitetop (Lepidium draba) galls we've found at our sites ...
08/07/2026

Happy Field Friday!
Today we're highlighting just a few of the whitetop (Lepidium draba) galls we've found at our sites across the state! The galls are caused by the whitetop mite (Aceria drabae). As plants develop in the spring, mites feed on the developing tissues & induce gall formation (a deformed appearance or abnormal growth that forms on the plant). Mites impact seed production and plant height over time, with the number of seeds decreasing as gall formation on the crown increases. Galls are typically visible from late spring to late summer.

Can you spot the difference?? One of these pretty purple flowers belongs to a native plant in the mint family that stabi...
08/06/2026

Can you spot the difference?? One of these pretty purple flowers belongs to a native plant in the mint family that stabilizes soil and provides high quality forage and habitat for native pollinators! The other is a classified 2B noxious w**d (see our previous post for more information regarding w**d classifications in Montana) that degrades wildlife and rangeland habitats, and outcompetes native species by releasing toxins into the soil.

Wild bergamot (Monarda fistulosa) is also known as beebalm and can be found natively across the state of Montana, and in most of the United States east of the Rockies. Bergamot is noted for its ability to grow in a wide variety of ecosystems and disturbed soils, along with its many healing properties. In addition to its role as a source of high quality forage for a variety of pollinators, the hollow stems of bergamot provide great overwintering habitat for small native bees and other cavity-nesting insects.

Spotted knapw**d (Centaurea stoebe) is a pervasive noxious w**d native to Europe, but found now in almost every state in the U.S. It has a deep taproot and individual plants can produce over 1000 seeds per year, making it quick to spread. Many pollinators will feed on knapw**d because it is what is available, but it has much lower nutritional value than our native plants. Knapw**d also produces a toxin called catechin, which acts as an herbicide to nearby native plants, killing them and allowing knapw**d to spread easier.

Biocontrol is an appropriate tool to help manage knapw**d populations and allow native plants like bergamot a chance to grow!
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W**ds! Learn more here... What are some other examples of w**ds you see in Montana? Do you know their priority ratings?
08/04/2026

W**ds! Learn more here... What are some other examples of w**ds you see in Montana? Do you know their priority ratings?

07/29/2026

Happy Weevil Wednesday! It's nearing spotted knapw**d root weevil (Cyphocleonus achates) collection time, and we CAN'T WAIT! Here's a short video of what some of the collection process looks like for us while we're out in the field.

Spotted knapw**d (Centaurea stoebe) was likely introduced to the US from the transportation of contaminated hay as early on as the 1890s. It can be a biennial or perennial with a deep taproot that releases a toxin in the soil damaging nearby plants. For this reason, and its rapid ability to spread, it has become a nuisance for many native habitats in North America.

Its pink flowers stand out from its spindly limbs and on these flowers is where we typically find the adult weevils. As its name suggests, “root weevil,” when in their larval form, they feed on the taproot limiting the nutrient uptake of the plant. With enough damage, they can effectively kill the plant. As adults, they continue to feed on the leaves, impacting photosynthesis.

When out in the field, we compare this collection to an Easter Egg hunt. You must train your eyes to spot them as their speckled pattern and colors help them blend in with the plants surprisingly well. On top of this, they like to hide from large moving things, so they often play ring-around-the-rosy with us as we reach down to pick them off the flowers or seedheads. We collect 100 weevils per release, and we love every second of it. Unlike most beetles, these ones don’t have functioning wings and elytra, so it’s important that we assist them with spreading to new infestations of knapw**d.

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Better together 💜 If you're out looking at a spotted knapw**d plant you may find not one, not two, but three of our bioc...
07/27/2026

Better together 💜 If you're out looking at a spotted knapw**d plant you may find not one, not two, but three of our biocontrol agents! These bugs can be so specific that their lifestyle depends on a certain part of the plant, meaning the combination of multiple biocontrol agents can be more effective in treating infestations. The spotted knapw**d moth (Apegata zoegana) and the knapw**d root weevil (Cyphocleonus achates) both attack the roots, while knapw**d flower weevils (Larinus spp) attack seed heads! Tag us in your photos if you find any of these cuties in the wild!

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Address

1075 South Avenue West
Missoula, MT
59801

Opening Hours

Monday 8am - 5pm
Tuesday 8am - 5pm
Wednesday 8am - 5pm
Thursday 8am - 5pm

Telephone

+14062584223

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