We Can Now Track Individual Monarch Butterflies. It’s a Revelation.

The New York Times ^ | Nov. 17, 2025 | Dan Fagin, Jonathan Corum

[E. Pluribus Unum]

Scientists used tiny new sensors to follow the insects on journeys that take thousands of miles to their winter colonies in Mexico.

A monarch butterfly carrying a tiny tag developed by Cellular Tracking Technologies at the Cape May Point Arts and Science Center in New Jersey, which helped fund a monarch tagging project.Credit...Video by Hannah Beier

For the first time, scientists are tracking the migration of monarch butterflies across much of North America, actively monitoring individual insects on journeys from as far away as Ontario all the way to their overwintering colonies in central Mexico.

This long-sought achievement could provide crucial insights into the poorly understood life cycles of hundreds of species of butterflies, bees and other flying insects at a time when many are in steep decline.

The breakthrough is the result of a tiny solar-powered radio tag that weighs just 60 milligrams and sells for $200. Researchers have tagged more than 400 monarchs this year and are now following their journeys on a cellphone app created by the New Jersey-based company that makes the tags, Cellular Tracking Technologies.

Most monarchs weigh 500 to 600 milligrams, so each tag-bearing migrator making the transcontinental journey is, by weight, equivalent to a half-raisin carrying three uncooked grains of rice.

“There’s nothing that’s not amazing about this,” said Cheryl Schultz, a butterfly scientist at Washington State University and the senior author of a recent study documenting a 22 percent drop in butterfly abundance in North America over a recent 20-year period. The movements of monarchs and other flying insects are cloaked in mystery, and “now we will have answers that could help us turn the tide for these bugs.”

Tracking the world’s most famous insect migration may also have a big social impact, with monarch lovers able...

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TOPICS: Science
KEYWORDS: butterflies; danfagin; jonathancorum; madscientists; monarchbutterflies; newyorktimes

[Red6]

My wife mentions that occasionally. She’s seen it.

I’d love to see that one day.

[Red6]

Is the polar bear meme real, or just funny?

[Dr. Sivana]

Give me the metric system any day.

Use your metric system when measuring your nanometers on modern chips.

I'll use metric for buying fish at the fishmonger when hectograms instead of grams or decimals of a kilogram because they cannot remember anything smaller than a factor of 1,000 for everyday weights. I'll take a pre-enlightenment system based on how people really live, than based on "the distance that light travels in a vacuum in exactly 1/299,792,458 of a second at mean sea level."

If they had to come up with an utterly arbitrary system (outside of celsius), why couldn't they make it base 12, so we can have quarters and thirds divide nicely?

[E. Pluribus Unum]

You probably did but were sabotaged by spellcheck.

[Carry_Okie]

I am trying to bring in native plants as I find them.

Annuals are the hard part, and the most important to diverse insect life. Even tiny weeds can suppress native annual germination. If you have that problem I may be able to share what I've done to make it happen, but it takes considerable time to learn visually distinguish native germination from weed seedlings. FRmail me if you have questions.

[NonValueAdded]

Of course, given the way butterflies fly, a one-mile trip covers a distance of 5.

[Harmless Teddy Bear]

It is both real and funny.

The polar bear population is indeed growing.

[FamiliarFace]

I used a habitat in August/September to help house Monarch caterpillars during a cold spell. I had 35 caterpillars and 31 successfully emerged from their chrysalises and flew away. It was a fascinating experience.

[Salamander]

Maryland decided to plant milkweed in the median strips of I70, which seemed like a brilliant idea.

However, they somehow did not foresee what would happen when newly emerged Monarchs flew out of the median strips straight into interstate traffic.

It was horrible.

[Fury]

Amazing this summer watching the high number of fireflies over the front meadow (used to be a lawn) vs adjacent areas that were mowed. A three acre meadow had over 4,000 fireflies as estimated by an entomologist that did a survey.

The non-native species that we focus on in the ornithology research area I maintain is Common Teasel. It fragments medians where ground nesting birds frequent. Since 2018 we’ve hand cut or pulled over 73,000 plants with over 15,000 in 2025. It’s spread primarily by improper late season mowing. In doing an off-season survey, the number of teasel basal rosettes that are wintering over is at a six year low. There’s several species of milkweed in the area and we do not disturb those as a general rule.

[Svartalfiar]

Most monarchs weigh 500 to 600 milligrams, so each tag-bearing migrator making the transcontinental journey is, by weight, equivalent to a half-raisin carrying three uncooked grains of rice.

I swear Americans will do anything to avoid using the metric system.

The metric system fails to be easily applied to normal sizes. English units, for the most part, make intuitive sense.

But the analogy might be better understood as the radios weigh the equivalent of a 200-lb person having to carry 20-ish pounds everywhere they go!

[Svartalfiar]

I'll take a pre-enlightenment system based on how people really live, than based on "the distance that light travels in a vacuum in exactly 1/299,792,458 of a second at mean sea level."

Well, the meter was actually defined as one ten-millionth of the distance from the equator to the north pole, on a line through Paris. The light speed definition was an arbitrary number that defined the meter by the speed of light, using the same size meter as previously defined, instead of using a more natural or even number.

[Svartalfiar]

They’re the only weed we let grow, cause of the monarchs.

If it's something you want to keep, is it really a weed?

[Dr. Sivana]

I know. So changes are made for whatever reason. It’s like the size of the king’s foot, only less frequent. They could have worked off of nautical miles, if they want to do the pole to pole thing. Does the size and shape of the earth change ever so slightly? Yes. Then you make adjustments as needed as we do with “leap seconds”. Thank God the calendar changes never took!