Histo-Research has a device called a “Dip” to travel in time and study the past. It is forbidden to go to the future, but Wood has done so at the urging of the Political Science Council. Somehow they introduced a lethal factor that at some future point will destroy the human race. Hasten, an expert, has been chosen to take a Time Car to the future and find out what has happened. Cities and cows remain, but no people. There are a great many enormous colored butterflies, one of which flutters up and stings Hasten’s hand. He is sick immediately, and the tissue in his hand and arm turns black and dies. He tries to find information in a library, but the newspapers are in another language. He debates his next actions as he heads back to the Time Car with some newspapers. Then he sees a swarm of butterflies. He gets into the Time Car but the butterflies descend upon it. They proceed to cut perfect circles into the ship and enter it, but Hasten kills them with a blowtorch. He returns swiftly and explains the situation to Wood. He seems somewhat optimistic that knowing what has happened, they may be able to stop it. Then Hasten sees that the Time Car is covered in cocoons, most of which are now empty. He has unwittingly brought the killer butterflies back with him.
- The Short Happy Life of the Brown Oxford and Other Classic Stories* by Philip K. Dick