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Spotted Knapweed Weevil Project at Candlewood Ridge

In 2021 GOSA botanist Whitney Adams identified a natural solution to the spotted knapweed infestation at the Sand Plains property. He discovered that a company called  Weedbusters Biocontrol offers USDA approved insects to control invasive plant species that have been introduced to the US. That summer Whitney ordered our first batch of weevils to attack the knapweed. One (Cyphocleonus achates) attacks the root of the plant while the other (Larinus minutus) attacks the flower. The effect of the weevils usually takes years while the insects multiply. However, our results were so dramatic we decided to deploy a second batch in 2022.

Note that the branch of the USDA that tests the weevils for import suitability is called the Animal Plant Health Inspection Service (APHIS.)  They subject each and every weevil imported to the US to make sure it feeds on only the target plant species. 

There are many other invasive plants at the Sand Plains (primarily Mugwort), but spotted knapweed is one less invasive we have to worry about.

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