Transcript
Gall Flies Help Control Canada Thistle
January 12, 2011
Event: Gall Flies Help Control Canada Thistle ______________________________________________________________________________

Gene Bolka, Mystic Ranger District
Wind sounds Today what we started to do, we’re actually trying to collect galls, which are made from the Gall Fly on the Canada Thistle, and what we’re going to do is reinduce them to another area and this time it’s gonna be up in the Wall area, Wall, SD, along the grasslands snapping noises What happens is, at least with the Canada Thistle is the Gall Fly lays its eggs on the stem of the Canada Thistle, and then once the egg hatches, the larvae burrow inside the plant itself, and then at that time it starts forming a gall. These insects are only attached to the Canada Thistle. They won’t attack your tomatoes, or alfalfa, or corn, or anything like that. These are site specific to Canada Thistle only. We try to use an integrated pest management system which are biological, chemical, and even mechanical. Mechanical is not necessarily going out here and cutting every Canada Thistle we see. It’s with cattle. We do have range cattle on the forest during the summer, and they actually will target Canada Thistle, in some of the areas if it’s at the right time. The big thing is budget. If we can get these, any of the biological control items free, or right off the land that we planted ‘em on that’s obviously a plus. We don’t have to spend any money. The only thing that we have is their time. We get to move the bugs across the state and, of course, they’ll start a insect area there where they can start their own bugs and start moving them wherever they need to like we do here. What we do is we put a metal stake in the ground or a T-post, fencepost, and then we go ahead and we release the galls in that particular area and we usually monitor that. If they release them in let’s say April; or February, March or April, in August, or even late July, they should be able to see galls forming on the Canada Thistle themselves. The way we do it is to monitor it with pictures. We take pictures when we release them. We take pictures, um try to get pictures every year after that to see if they’re spreading out from that particular post.

The people that use biological controls should be aware that it’s not a you drop ‘em off today and tomorrow all the thistles are gonna be gone. It’s a long term program. It’s good for maybe three to five years. Once you get on to that you should have enough to kind of really limit the Canada Thistle on your property, or in a particular area, but you still have to use some kind of other control to make sure that them plants do not move across boundaries, or into your neighbor’s yard or whatever. So you’re gonna have to put the bugs out if you want, or go around and spray still with the chemicals.