Fossil True bug, Heteroptera , Miridae in Baltic amber for sale. Aphids probably first appeared 280 million years ago, in the Carboniferous period. They probably fed on non-flowering plants like Cordaitales or Cycadophyta. The oldest known aphid fossil is one of the species Triassoaphis cubitus from the Triassic. There were relatively few species of aphids at that time, and the number of species only considerably increased since the appearance of angiosperms 160 millions of years ago. This is due to the fact that angiosperms provide an occasion for aphids to become specialized. Aphids have not always looked like they do nowadays. Organs like the cauda or the siphunculi were not evolved until the Cretaceous.