What problems do invasive species cause ?
Here is an attempt at a partial answer.


  What is so bad about invasive species ?


Invasive species have been introduced to a new habitat by humans (or by natural means). 

They usually do not have a predator in a new area nor are the pathogens in the area very adept at infecting them. So, they may proliferate rapidly and compete with the native species. They may also be ferocious predators as their preys do not have defenses against them.