Monarchs Rule

We stopped again at the Pismo State Beach Monarch Grove. At 2:00 p.m. Docent Ernie delivered a butterfly talk. He explained that no monarch crosses the Rocky Mountains, and all eastern monarchs winter in Mexico. Western monarchs winter at 300 sites in California. Four of those are major sites, usually with Pismo Grove as the largest. This year Pismo is the winter home to about 16,000 butterflies. Ernie said the number varies yearly based on the milkweed available, from a low of about 15,000 insects since they started tallying to a high of more than 200,000. The past four years in California have been dry ones, so less milkweed as food for caterpillars means fewer monarchs.
"The count must be unscientific," said Andy."
Ernie explained that a professor and students count the number of clusters in the cold early morning and then count how many individuals cling to an accessible branch in one cluster. That is multiplied by the approximate number of clusters in the reserve at any given time. Butterflies cluster at night to keep warm, since they can't fly when temperatures dip below 55 degrees.

"Yup," said Andy, "highly unscientific."

We also learned that the monarchs we watched would live in Pismo Grove without eating until mid-February. Then the males, those with two small black dots on the lower wings, would know it was Valentine's Day and would look for a mate. When pairs come together, they fall to the ground in the Grove. Then the male carries the female to the tops of the trees. "It sort of sounds like a honeymoon," I said to Andy.
By March 1, pregnant females flutter north about 200 miles, looking for milkweed plants. They lay eggs smaller than the size of pin heads on the underside of milkweed leaves before they die. The eggs hatch and the caterpillars eat for nine days, more than 27 times their body weight, shedding their skin as they grow. With the last shedding, each larva attaches itself under a solid surface, wraps itself into a "J" shape and forms a chrysalis. What emerges is an adult butterfly that heads north another 200-300 miles.

Five or six generations of insects later, the adult that will winter in Pismo arrives at the northernmost range, like Vancouver or Victoria on the West Coast. Suddenly in late August or September that monarch knows to fill up on nectar for the 1,000-1,600 mile flight back to Pismo Beach, arriving by early November for the winter.

"So the butterflies at Pismo do nothing all winter," said Ernie. "Their job is to survive so that five or six generations hence there will be other monarchs that can fly back to Pismo."