The Whitehall Ledger - Serving Southern Jefferson County in the Great State of Montana

By Todd Breitenfeldt
Project Director 

Busy year for the Whitheall Project


August 7, 2019

The Whitehall Biological Weed Control Project has had a busy year. We started June 1st and have collected/released the following numbers so far:

Mecinus janthiniformis (Dalmatian toadflax stem weevil, collected near Missoula and Helena): 4,100 = 41 releases. Collection season done.

Jaapeilla ivannikovi (Russian knapweed gall midge, from the Whitehall insectary): 30 galls (a gall is a swelling on the plant that contains multiple larvae) = 10 releases. Collection season done.

Aulacidea acroptilonica (Russian knapweed gall wasp): 70 galls = 10 releases. Collection season done.

Aphthona spp. (leafy spurge flea beetle, collected near Grass Range, and some from just south of Whitehall): 156,00 = about 156 releases. Collection season done.

Oberea erythrocephala (red headed leafy spurge root boring beetle): 800 = 8 releases. Collection season done.

Cyphocleonus achates (knapweed root boring weevil): 1,600 = 16 releases (we are just starting this insect and hope to collect over 150 releases to meet our demand).

We are now in the start of Cyphocleonus achates which is a bit late because of all the cool weather we have had this spring/summer. Feel free to contact us if you would like a release: Todd: 406-498-5236 or Alycia: 406-565-3995 during normal business hours, please.

We occasionally remind you of the insects we used to collect but, have become so well established in the area (with the help of many of you!) that we no longer need to collect and redistribute them. One such insect is the knapweed root boring moth Agapeta zoegana. This small yellow moth (about 11 mm) was first reared for release in the Montana at the MSU Ag. Experiment Station in Corvallis in the 1980's by researcher Jim Story. We started to release, rear and collect them in the 1990's. Slowly through the efforts of many Montana weed fighters, these moths have been redistributed and have spread themselves by flying, throughout the State. I find them in medium/variable numbers almost everywhere in Montana that has knapweed. They do damage the roots and weaken the plants but, usually do not kill the plant like Cypho does. We used to collect them out of our insectary here at the WHS track and from a site just east of LaHood along the Jefferson River. We no longer need to because they are so well established all over!

Pictured is a larva in a knapweed root. Note the feeding damage to the inside of the root.

These moths start emerging from their pupae in June and continue to emerge through August. The adults are short-lived, mate within 24 hours of emergence, and the females lay between 21-78 eggs. Like many moths, they are most active in the early morning or evenings. The eggs are deposited on the leaves and in stem crevices. Minute larvae hatch in 7-10 days, migrate to the root crown and mine (eat the inside) of the roots. They develop through six larval instars (shedding of their exoskeleton). The larvae overwinter in the roots, feed more in the spring and pupate in the roots in late spring. The adults emerge that summer as mentioned above and do it all again. There is usually only one generation per year. You can find these small, yellow moths around porch lights everywhere knapweed occurs.

It is the larvae that do the damage to spotted and diffuse knapweed. They weaken the plants but, do not usually kill them. The moth disperses well by flying. They have become an established part of the "team" of about 12+ insects that have been released on knapweed in Montana so far. The most effective being Cypho, the knapweed root boring weevil that we will have available as mentioned above.

So, as you see knapweed this summer (those pretty but nasty purple blossoms!), think of the silent weed fighting Agapeta moths busily living out their lives helping to weaken knapweed and bring it more into ecological balance in our North American environment.


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