Learn About Whitehall Bio Control: 6/21/2023

The crew is having a hard time finding many Dalmatian toadflax stem-boring weevils so far this spring. We have had good collections in the Missoula and Clinton areas for the past several years. This year we went there on June 14th to collect and the cool wet, windy weather plus the site crashing made it hard to find many weevils. The site "crashing" means that many of the weeds have been killed by the bioagent so because of a lack of food, there are not many insects left to collect. This is only a problem for us, the landowners are ecstatic! It happens to us often; we just try to find new collectable sites throughout the state.

We had requests for 65 releases and were only able to collect 10. We will try again on June 22-23rd, weather permitting. This toadflax stem boring weevil is becoming very widespread throughout Montana. Because of this, we will in future years decrease our collection efforts and do more to monitor the spread and effects of the weevil.

We also collected two releases of the yellow toadflax stem boring weevils in the Rock Creek area. They are even more effective than the Dalmatian toadflax weevil and thus are rarer and harder to collect. In many places, yellow toadflax has all but disappeared due to this insect! We mass rear some of these fine little weevils at the insectary at the High School. We collect several releases there every year for distribution. We are trying to get this insect established on every patch of yellow toadflax in the area.

It is nice to see a cold, wet spring! Hopefully, we will be breathing less forest fire smoke later this summer!! However, this cool weather is causing many of our State designated noxious weeds to sprout all over the place and putting our insect species' emergence 2-3 weeks behind most recent years. The next insect we will collect is the leafy spurge flea beetle(s). It looks like this will happen in July.

These leafy spurge flea beetles are small hopping beetles with strong back legs like a grasshopper or flea. The minute larvae eat the roots and really knock back leafy spurge on dry sites. They do not work on wet sites such as along ditches, streams, and around ponds as the larvae drown but, the darn spurge does not. Flood irrigating and heavy watering will also kill the beetle larvae. We have many requests for these insects so we shall see how the July collecting goes.

The flea beetles are also becoming widespread throughout Montana, so we are slowly curtailing our collection/distribution efforts and are doing more monitoring for dispersal and long-term effects. The "good-ole-days" of collecting a million bugs in a day are over as all the large "super-sites" have crashed. We can still collect some so feel free to request a release if you really feel you need one. Call Todd at 406-498-5236 or Brynna at 406-202-2393 during normal business hours.

Sheep and goats will eat leafy spurge but usually do not kill it. Keep up the good effort to control noxious weeds on your land!