As it happens, I just got back from seeing the Monarch grove in Mexico. It's an amazing sight. When the sun comes out from behind the clouds and they all warm up and take off within a couple minutes, the air is so full of them that they darken the sky. And the mountain (in Michoacan province, about 2 hours by car from Mexico City) is beautiful and the people are friendly. If you've seen the Monarch groves on the California coast, Mexico has 2 orders of magnitude more. Well worth the trip.

Our guides, showing WWF slides, told a more optimistic story about numbers. They had declined to very low levels around 2011, but have bounced back substantially. They said the small decline in the last 2 years might be normal variation due to weather. The graphs showed random variation in population by a factor of 2 from year-to-year going back to the 1970s, so it's probably hard to conclude anything from a single year's count.

Still, if you live along the migration corridor, please plant milkweed and don't use glyphosate weed killer.

I grew up next to meadows that were rarely if ever cut, in the 1980's (Northeastern US). As a young child I'd often find Monarch caterpillars, and was sometimes allowed to keep them in a small, strange box molded from glass and known as a terrarium. I'd feed them milkweed until they reached the pupal stage, then watch with wonder as the chrysalis changed from a jade-like, gold-rimmed ornament into a transparent capsule of folded orange-black wings. Finally, when the new insect emerged, we watched and waited (with still more patience) for the wings to dry, leading up to release day, when the butterfly was suddenly gone in a dash toward the sky.

Guided by my grandmother, an amateur naturalist, these were my first experiences leading to a knowledge of change, lifecycle, and above all the beauty to be found in the natural world. This simple gestation process of a curious looking caterpillar is impressed on me like no other early childhood memory. A process taking weeks, it was my first consciousness of time.

Today, those meadows are acres and acres of trimmed lawn. The smooth aesthetic of green grass pocked with dandelion has won over the wildness of a milkweed dotted field. But me, I've forsworn all lawn mowing, and should I ever own a meadow, will let it go to seed.

The assertion here by this activist group that the decline is due mainly to herbicides used on GMO crops doesn't seem to hold up on closer inspection:

https://www.washingtonpost.com/national/health-science/why-p...

https://geneticliteracyproject.org/2016/11/04/save-monarch-b...

We can help the humble Monarch butterfly by planting milkweed seeds:

https://www.thebutterflyfarm.com/free-milkweed-seeds-0

Ever notice how about 15-20 years ago while driving on the highway your car would be covered in bugs? And now hardly any.

If it helps, milkweed is also known as "swan plant" due to the shape and colour of the flowers. Can help convince some gardeners to invest, if the word "milkweed" puts them off as it sounds unpleasant.

it was worse before - we have at least 1 year http://monarchwatch.org/blog/uploads/2018/03/monarch-populat...

Iowa plans to plant milkweed state wide to help the Monarch recover. All part of a national effort.

http://www.kcrg.com/content/news/Planting-a-billion-milkweed...

Almost sounds touchy-feeling, until you get to this part (of the link above)...

"... The Endangered Species Act has tremendous impact on private land ownership. And so we don't want to get at a point as a partner with DNR with our other partners out there, we don't want to get to the point where there is no choice but to do this then it becomes mandated under the endangered species act. We'd rather have voluntary participation."

tl;dr; If the DNR shows up, we'll finally have to do something about our water quality.

I was in Monterrey and San Luis Obispo last December and ran into the Monarchs on their way migrating down south. It was quite a sight catching them randomly on forest hikes: https://i.imgur.com/315pC3y.jpg

Has anyone ever bothered to ask themselves that the ridiculous propagation of the idiotic ritual killing of every terrestrial arthropod by suburbanites throughout every municipality east of the Mississippi might actually be a major contribution to this outcome?

Anecdata. I live in the same place I grew up. As a kid, the monarchs passing through was a fun part of the season. Thousands and thousands of butterflies over a few weeks or so. Now, we are lucky to spot a single monarch.

We planted milkweed at our home, 9 years ago in Colorado, but never saw any visiting Monarch.