"Scientists said the decline appeared to be driven by hot, dry conditions in the United States and Canada that reduced food supply."

"The number of monarch butterflies at their overwintering areas in Mexico dropped precipitously this year to the second-lowest level on record, according to an annual survey.

The census, considered a benchmark of the species’s health, found that the butterflies occupied only about 2.2 acres of forest in central Mexico, down 59 percent from the prior year. Only the winter of 2013-14 had fewer butterflies.

Scientists said the decline appeared to be driven by hot, dry conditions in the United States and Canada that reduced the quality of available milkweed, the only plants monarch caterpillars can eat, as well as the availability of nectar from many kinds of flowers, which they feed on as butterflies."

Catrin Einhorn reports for the New York Times February 7, 2024. [2]