Last summer the population of Monarchs
in the Northeast United States seemed to be greater than it had been in
the past decade. This was consistent with the fact that the number of
butterflies making it to Mexico for the 2018-19 winter was the highest
since 2006-07 (see graph). Unfortunately, only half as many made it to
the overwintering forest this past winter, perhaps due to unfavorable
weather on the return trip. [1 ha = 2.47 acres is about 50,000,000
butterflies, so more than 100 million butterflies are heading north this
year.]
A remarkable 3-minute film of a ‘hummingbird’ drone spying on the Monarch population in Mexico is available. Be sure to watch to the spectacular conclusion at the end!
The Monarchs are now moving north as shown by the map below, with the
long-lived overwintering generation producing the next generation early
in the trip. The annual circuit from Mexico to Canada and back takes
4-5 generations.
BTW, it has been found that breeding Monarchs indoors does not generally
produce healthy Monarchs who know where they should be headed. The
best way to help Monarchs and observe their marvelous transformation
from larvae to butterfly is by planting milkweeds, their only food.
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