Yeah I had no idea either, but so far it seemed like we are rid of them!
Its soo tasty to have fresh asparagus, the flavour is so incredible.

We got two patches, one is 8 - 10 feet long and 3-4 feet wide and the other one is about 5 feet wide and 7 feet long. The spears it produces are crazy thick, about an inch in diameter. Before we moved in nobody was really harvesting the asparagus, its just been abandoned for a couple of years. But the patches are old.