Number that over-wintered in Mexico were up 64%
The World Wildlife Foundation reports the Monarch butterfly population in Mexico in December of 2025 covered 2.93 hectares, an area sixty-four percent larger than they covered in 2024, and slightly ahead of the ten-year average (2.81 ha).
That jibes well with what we are seeing here, after a very desolate summer in 2025, Monarch-wise. Regular watchers Cathy Hoard, Dave Elder, Kristina Fulton, and Tom Nash have all reported sightings.
“There have been butterflies about for just over a month… not tons, but some,” said Nash. “There seem to be significantly more right now than the scant few original sightings might have foretold.”
“There are a good number of caterpillars varying from tiny newly hatched to just about ready to form their chrysalis. So starting in about two to three weeks, there should be significantly more adults flying about, looking for milkweed and sex. Really, who can blame them?”
These tiny creatures have an amazing life story. They over- winter in a small area of Mexico, millions upon millions of them, and start a northward migration every spring. When they reach the southeast U.S., they mate and lay eggs and leave it to the next generation to continue the northward migration. Those Monarchs reach Canada in mid- to late-May, where they mate and lay eggs through August.
Their progeny, that final generation “will begin one of the most astonishing insect migrations in the world, flying south through half the continent, a distance of up to 5,000 kilometers, to return to the ancestral winteing area in Mexico,” says Dave Elder.
Want to see Monarchs? It’s very simple: plant Milkweed, the only thing they eat. If you plant Milkweed, a hardy perennial, in your yard (as Hoard, Elder, Fulton, and Nash have all done), the Monarch butterfly will find it.
“If you don’t have milkweed tucked into your garden, one might reasonably ask why not…” says Nash.
Continental count
For the past nine years, citizens across North America have been contributing their observations to the International Monarch Monitoring Blitz. For eleven days (this year, it is from July 30 to August 9) iNaturalist Canada.ca will accept reports from Canadians.
The Monarch Blitz invites people across North America to look for monarch butterflies and milkweed plants and examine them for monarch eggs, cater- pillars, and chrysalids (co- coons). Monarch Blitz data are uploaded and shared via the Trinational Monarch Know- ledge Network, a repository that combined data from various sources to assist researchers in performing large-scale temporal and spatial analyses.
The data collected by volunteers (9,000 last year) help researchers answer key questions about monarch butterfly and milkweed distribution, the timing of their reproduction this year, and details about their habitat use. In turn, this information helps conservation practitioners identify and prioritize actions to conserve the species and its habitat.
Search ‘International Monarch Monitoring Blitz’ at www.iNaturalist.ca to participate.
