What is The last name of the naturalist who classified the monarch in 1758?

Carl Linnaeus

Explanation:

Carl Linnaeus was the Swedish botanist who classified the monarch butterfly for the first time in 1758. He was also the creator of the modern taxonomy system that we use today to classify plants and animals.

The taxonomic system developed by Linnaeus is called the binomial system because the name of every organism is made up of two parts. These were originally only from Latin, but can now be adapted from any language.