Great Lakes Hydrilla Collaborative
How does it spread?

The primary vector of spread is by hydrilla fragments on recreational boats and trailers. New colonies are often found near boat ramps where stem pieces have become rooted in the substrate.

There are additional mechanisms that may spread hydrilla fragments, such as waterfowl and aquaria, but these other vectors are not well understood. While these vectors may serve as potential transport mechanisms for hydrilla, they do not do so at the same frequency as boats.