May 112014

Monarch butterfly on Tithonia, a favorite nectar plantMary J. Metzger

Monarch butterfly on Tithonia, a favorite nectar plant

Last summer I saw only one Monarch butterfly in my pollinator garden. And that was at the end of September when it should have been making its long migration back to its winter home in the mountains of central Mexico.

The decline in population may be a trend that people are noticing, and can do something about. Not being able to do anything about the weather, gardeners concerned with the butterfly’s survival are trying to make sure there are milkweed plants everywhere along the Monarch’s migration routes. The Groton Public Library will present: Gardening Get Together: Monarch Butterfly Waystations, Tues, May 13, 7-8 pm. Guest speaker Carol Satlar volunteers with and will explain how to help people plant milkweeds, the host plants for monarch caterpillars and nectar plants for adult monarchs.

After adult Monarchs spend the winter there, huddled together in oyamel trees in a tiny 5-50 acre area, they move north, reproducing three or four generations by the time they get to Groton. Last year’s cold spring and summer drought in the Midwest caused Monarch population counts everywhere along the journey north to drop drastically, following a trend that places their numbers 90% lower than the averages in the 1990s.

Adult butterflies feed on the nectar of many flowers, but their caterpillars can find food only on milkweed plants. Changes in agricultural methods have eliminated the milkweed plant that used to be common at the edges of fields.

This year’s Monarch path can be followed on maps at Journey North,, a citizen scientist website that reports the first sightings. Scientists use this spring migration data to explore connections between arrival time and reproductive success during the breeding season.

Dr. Chip Taylor of Monarch Watch,, predicts how this year’s population will fare based on his Three Bears hypothesis: “There’s an optimal time of arrival in the northern breeding areas — too early or too late usually leads to lower production. Overall, we seem to be off to a better start than in either of the last two years — too hot in 2012, too cold in 2013 — just right in 2014? Not quite, but there is hope for some recovery.”