Trees, man.
If you take the environmentalist view of humanity, we are a plague. We spread to the corners of the world, we destroy ecosystems that aren't centralized around ourselves, we choke out other species who can't compete, we even choke out ourselves in direct competition. We release noxious fumes that ruin the air quality, and we potentially cause mass extinctions through all of these things.
But all of that description is less accurately applied to humans than it is to trees. Trees are everything people are criticized for and worse. Some trees drop herbicidal chemicals from their leaves and needles so that no other plant can grow near them. Some trees depend on burning whole ecosystems to the ground in order to propagate. Trees use as fuel and lumber was the seed for human technology to sprout from. The climate changing from the burning of carbon based fuels traces straight back to trees. There is nothing so ironic as the environmentalist embrace of trees as a symbol of nature.
And here we are at a moment in time with the trees in the western US are all burning down from their insistence on growing in a climate that can't support them without fire, while in many parts of the world people attempt to "fight climate change" by planting millions of trees in places that likely can't support them without them eventually setting on fire.
Trees, man.