The New York Times – no paywall: “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. Dan Fagin is writing a book about monarch butterflies and the future of life on a human-dominated planet. He has twice visited the Mexican colonies and thinks everyone should at least once. 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..

Tracking Monarchs – Two monarchs known as LPM021 and LPM084 were released on Sept. 13 and 28 in Long Point, Ontario. They flew past Mexico’s Monarch Butterfly Biosphere Reserve, where the largest colonies are located, toward smaller colonies to the southeast…”