In On the Origin of Species, Darwin wrote that bumblebees are the only species that pollinates red clover. He discovered in 1862 that honeybees also pollinate red clover. Prompted by this discovery, he wrote to his friend John Lubbock, saying, “I hate myself, I hate clover, and I hate bees.”
Six years into his studies of barnacles, he wrote "I hate a Barnacle as no man ever did before, not even a Sailor in a slow-sailing ship."