Monarch Butterflies

Stacey and Rick discuss the annual migration of North America’s monarch butterfly.The monarch makes a two-way migration as birds do. The monarchs know when it is time to travel south for the winter. Some fly as far as 3,000 miles to reach their winter home! Monarchs in Eastern North America have a second home in the Sierra Madre Mountains of Mexico. Monarchs living west of the Rocky Mountain range in North America overwinter in California along the Pacific coast near Santa Cruz and San Diego. The microclimatic conditions are very similar to that in central Mexico. Monarchs roost in eucalyptus, Monterey pines, and Monterey cypresses in California. Monarchs in Western North America overwinter in California, places like Pacific Grove CA “Butterfly Town USA” Monterey CA or San Luis Obispo.

The number of hectares (About 2.47 acres make up one hectare, so an acre is only about 40% of the size of a hectare) that monarchs cover when overwintering in Mexico is a good gauge to watch trending for their population size. Think about the trend over five years, or 10 years or 20 years. The trend has been for reduced populations. That long-term trend is the reason the monarch was listed as endangered by the International Union for Conservation of Nature (IUCN) in 2022.

Stacey and Rick discuss common Milkweed (Asclepias syriacus) and Butterfly-weed (Asclepias tuberosa) There are a number of key differences between butterfly weed and milkweed. Most common milkweed plants have pink or purple flowers, while butterfly weed plants have orange, yellow, or red flowers. When it comes to attracting pollinators, both of these plants do a good job, but Rick suggests that the common milkweed (Asclepias syriaca) is better for the caterpillar stage than butterfly weed (Asclepias tuberosa) for monarch butterfly reproduction. Both belong to the Asclepias or milkweed genus. Stacey very much disagrees and shares examples of butterfly weed in her yard as just as valuable for the caterpillar stage. We learned something new.

Word of the day: They arrive in October after their journey from the USA, and cluster together in a near hibernation-like state known as (Word of the day): torpor a state of lowered physiological activity typically characterized by reduced metabolism, heart rate, respiration, and body temperature that occurs in varying degrees especially in hibernation.
Rick suggests following the website

Excerpt: (from last week) “There is no change in the forecast. Temperatures will remain higher than usual for this time of year. This weather pattern appears to be widespread across México. It is now reaching the fir forests located 10,000 feet in elevation. Usually, temperatures under their canopy are cooler, just right for overwintering monarchs. Reported temperatures are the warmest and driest we have experienced during these winter months. February and March could still bring winter effects, as has occurred in the past. We are all waiting to see if the weather changes.”

Monarch butterflies have four life stages: egg, larva (caterpillar), pupa (chrysalis) and butterfly. Adult monarch butterflies typically have four generations each season. The ones most visible in late summer and early fall are the fourth generation, which are the ones that will migrate thousands of miles to Mexico, they are biologically different from previous generations. They live longer and do not mate or lay eggs until the following spring after they fly north and reach areas with milkweed.

Rick suggests the website: for milkweed seed.

Milkweed seed was used during World War II to fill life vests and save sailors and airmen. Rick shares an excerpt from one of his books: Late in the growing season along the Lake Michigan shoreline, common milkweed Asclepias syriaca is distributing its seed. The seed pods jettison their flat brown seeds attached to tufts of silky fibers or floss. The pods split open along a central seam and then like parachutes are carried aloft by the wind. Milkweed is named for its characteristic milky sap or latex. Some prefer to call it silkweed due to the proliferation of the “seed floss” distributed when the pods crack open. It’s an ingenious and natural propagation insurance for the distribution and continuation of the species much to the merriment of the Monarch butterfly. During World War II Dr. Boris Berkman, a Chicago physician and inventor had other ideas than a natural distribution. He wanted them harvested and used for the war effort. The milkweed long considered by many a nuisance weed, in his mind would come to the rescue of aviators and sailors. For years, kapok would be used as the typical filler for floatation devices. The tree Ceiba pentandra produces a light and strong fiber known as kapok and it was used to fill mattresses, pillows and yes life preservers. Kapok was cultivated in the rainforests of Asia and Indonesia (Dutch East Indies). With the world at war including the Pacific the supply of this important filler was cut off. A replacement material was needed to spare the downed pilot or overboard sailor and Berkman had the solution. The common milkweed. Not only was milkweed plentiful in North America it could arguably do a better job than kapok as filler in life vests. Tests conducted by the U.S. Navy showed that a little over a pound of milkweed floss could keep a sailor floating in the water for hours.

Great plants for Monarch butterflies:

  • Common Milkweed (Asclepias syriaca)
  • Swamp Milkweed
  • Butterfly-weed (Asclepias tuberosa)
  • Buddleia
  • Caryopteris
  • Clethra
  • Itea
  • Coneflower/echinacea (Stacey suggests the single flower types over doubles, which replace pollen and nectar-bearing parts with petals)
  • Verbena
  • Zinnias
  • Rudbeckia
  • Helianthus and Heliopsis
  • Joe Pye Weed Eupatorium
  • Asters
  • Monarda
  • Liatris

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