Answer: It's their work as crop pollinators.
Explanation:
We need the article in order for it to be complete
The answer is thesis I’m pretty sure
Every year, millions of monarch butterflies migrate from the forests of Canada and the northern United States to the forests of Michoacán and the State of Mexico where they hibernate and reproduce. During the summer they return to the north of the continent, and are usually carried out by the descendants of those who emigrated to Mexico