Invasive Species

Leafy Spurge FWS 512 X 219

There are many invasive species on the refuge, including leafy spurge shown above.  Some others include Canada thistle, houndstongue, smooth bromegrass, kentucky bluegrass, and Absinth wormwood.


Leafy spurge, once one of the worst invasive species problems on the refuge is largely reduced and held in check by a successful biological control program.  Flea beetles of the genus Apthona spp. have reduced leafy spurge by feeding on the plant, both in summer as adults and in winter as larvae feeding on the extensive root systems. 

Flea Beetles on spurge Jewett 150X118 


Biological control is also being used to combat Canada thistle with leaf mining weevils.  

Houndstongue is being battled with hand pulling and herbicide treatments.  

Absinth wormwood has spread significantly on the slopes of the valley due to the inundation of the refuge several times in the past 5 years with extreme flooding, which deposited seeds on the banks and then the water receded, creating ideal germination areas.  It is also difficult to access those steep slopes on the refuge near the waters edge.