Devil Weed (Chromolaena odorata)

[Midnight Rambler]

It's bad, bad, bad. It's a composite so it has tiny wind-blown seeds, and they also catch in things and spread around that way. It first showed up at the motocross area in Kahuku on Oahu, and spread around there by the dirt bikers. They tried to eradicate it but the main infestation is so dense it's impossible, and people keep going up there and spreading it around to new sites. On Big Island it first showed up at the Waiakea ATV park on Stainback so that's probably how it got here too. On other Pacific islands it's so bad in places that they've had to abandon farms because it grows so dense and is an irritant when you try to remove it.

It is kind of similar to some other weeds here that aren't so bad, but those are still weeds so it's still fine to pull them out. If you do find it, keep checking because the seeds will keep germinating for a few years.