Having been in agriculture my entire life, I have fought puncture vines for as long as I can remember. When I came across these puncture vine weevils in 1989 I got very excited.
That year, I released some weevils at my home in Umatilla, Oregon where puncture vines grew where nothing else would. I did not release as many as was recommended and the first year I saw very little activity. I was told our winters were to hard, and because they came from mild climate locations, not to expect their survival into the following season.
I did not think much more about it until later the following season, I noticed puncture vine seeds with a small hole in the side. Upon further inspection, I found small larvae inside the seed eating the viable portion of the green seed. Then I realized the previous winter had been quite mild, and they had obviously survived. We have not had a Bad winter yet, and I still have weevils on my place, from 1989.
This has reduced my Goathead population dramatically. From the time, I turned my weevils loose; I pulled fewer and fewer goatheads. Now I have very few goatheads. I have been told a Goathead seed can remain in the soil for 20+ Years, just waiting for the right conditions to germinate, and I do not doubt it a bit.
In the fall of 2002 I found a puncturevine growing next to my fence in the back yard. I pulled the plant and found only 3 seeds not being eaten by Puncturevine Weevils. That’s out of 34 total seeds on the plant. What a wonderful sight that was!
I have found Puncturevine Weevils all over our town. They have moved to everyone’s yard and parking lot alike, doing what they do… eating puncturevine seeds and only puncturevine seeds.
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