The Colorado beetle and the potato blight are considered invasive species, they are also often called plant destroyers.
The Colorado beetle did not originate in colorado despite the name, it was originated in Mexico. The colorado potato beetle used to feed on buffalo bur which is similar to an actual potato. The beetles spread around and were discovered taking over a farmers plants in Colorado. The beetles spread because of transportation methods, they would bring themselves on the trade ships and would often go unnoticed because they are so small. They spread to North Carolina, Wisconsin, and Maine.
The potato blight originated in Peru from Peru it traveled to Belgium China and since China was trading with Europe it eventually traveled to Europe and since Europe was trading with the Untied States it ended up in the United States also. Passengers on the ships began to notice strange spots on the potatoes. The potato blight destroys farmers potatoes, often times they go unnoticed as blights and are thought to be just a fungus. The blights flat around in the wind until they find a potato that they can land on and hatch. Once the blights land they send out zoospore, which is what destroys the plant. These zoospores are cells that go throughout the plant looking for stomata. They send a filament through the stomata which make the plant send nutrients to the filament rather than the plant. The filament is basically stealing all of the plant's nutrients which are what kills the plant. The plants to begin to turn brown and look unhealthy the plants die within days of being infested by the filament. The potato famine hit Ireland after the farmers planted more than two million potatoes, barley any of the potato plants survived. The Irish economy crashed because they often depended on potatoes for their income. The famine in Ireland was caused by the blights, they were what destroyed the crops. Many people and families began to die due to starvation because they relied on potatoes as their main food source. Both of these invasive species are very difficult to get rid of and almost impossible. By trying to get rid of these farmers indirectly made them spread more, they did not realize these invasive species would begin to flourish. The beetles have grown immune to much things that try to destroy them from eating plants.