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News: 09/01/2018

Monarch butterflies – raising the migration generation

monarch in a hand
By Katrina Aimo, Swede’s Feeds

Two years ago, when we first started planting milkweed with the intention of helping the endangered monarch butterfly, we met a man who was even more nutty about monarchs than we were! Merle, lives less than 10 miles away from Swede’s Feeds, has been tracking monarch activity around the Bay Area for a long time. He has been raising butterflies and keeping track of the West Coast migration for years. Normally, he had hundreds of caterpillars and chrysalides in his own backyard, but two years ago he had only two caterpillars. Meanwhile at Swede’s Feeds, we were getting all the action. We met Merle on his hunt for the missing butterflies. The past two years, he hadn’t had much luck. Now the tables have turned. The monarchs have not been seen in Kenwood and have returned to Merle’s. He has generously given us three armies of caterpillars this season. We could not be more grateful.

So far this year we have raised and released more than 20 monarchs. We currently have 15 caterpillars and more than a dozen chrysalides, due to emerge in the next week or so. Although we have eight milkweed locations with four different species, three of which are native milkweeds, we found no caterpillars or even monarchs in our garden at Swede’s. Why? We are uncertain, but have guessed it could be just the ebb and flow of natural cycles.

Danaus plexippus, our iconic monarch, translates from Greek meaning “sleepy transformation.” This describes the hibernation these insects endure in the colder months and then the incredible metamorphosis they make from larva to chrysalis to adult. When we think of amazing migrations, whales, sea turtles, sea birds, caribou and elephants come to mind. These larger animals migrate every year to sites around the world, to places they have physically been to before. They do this annually as the seasons change in search of food, breeding grounds and more tolerable weather. What is perhaps most astonishing about the monarch is that it migrates from its northernmost territory down south to its winter hibernation grounds, to which it has never been. That’s right! This tiny insect, weighing less than a dime, whose migration is second only to certain species of dragonflies in the insect world, will instinctively fly south to the exact same groves of trees used by its ancestors. Incredible!

Monarchs are found in the Americas, Pacific Islands, Caribbean, Australia and New Zealand. There are colonies that do not migrate because the climate is so tropical that the milkweed grows year round. These colonies exist in Florida, the Caribbean, Hawaii, and parts of Central and South America.

Monarchs that make the migration along the West Coast out of their wintering groves in Southern California travel north, sometimes all the way to the Canadian border. For the monarchs traveling along the East Coast and through the Midwest, their migration can be upwards of 3,000 miles from groves in Mexico to the southern territories of Canada. In both cases, it takes several generations to spread to the furthest reaches of their summer grounds, with an average lifespan of two to five weeks as a butterfly.

When monarchs are signaled by the changing of the seasons, the southward migration is endured by a single butterfly. These “super butterflies” make the entire flight back to the overwintering groves for the first time. In California, there are about 25 known winter roosting sites along the coast. These groves consist of eucalyptus, Monterey pines and Monterey cypress. The Eastern migrators make the flight from as far north as Canada to the 14 known sites in the trans-Mexican volcanic mountains. All these overwintering grounds have proper humidity, are lacking in freezing temperatures, and the trees serve as a natural wind barrier to protect them for the months to come. This super generation has a lifespan of six to nine months. They begin traveling south, hibernate throughout the winter and make the first trek up north in spring to mate and let the next generation continue the migration. The farthest ranging monarch recorded was 265 miles in one day.

The monarch population has declined over 90 percent since the 1980s. Only one out of 100 caterpillars will make it to adulthood. Lack of milkweed, habitat loss, pesticides, herbicides and predators are all effectively dampening this species’ survival. Even organically certified products can affect these creatures. For instance, BT (Bacillus thuringiensis), which is legally used in certified organic gardening, proves harmful. Predators including spiders, ants, dragonflies, yellowjackets, wasps, and tachinid flies will prey on the caterpillars, while birds, yellowjackets, wasps, and mantis will prey on the butterflies. Mice have even been known to eat the chrysalides. This is why we bring our caterpillars “indoors” to keep them safe and enhance their chances of survival.

So, what can you do to help monarchs in your yard? First, and most important, you will need plenty of milkweed. Milkweed needs eight or more hours of sunlight and it needs space. Some varieties grow five feet tall. If you can’t set up a vivarium or some safe space indoors for your caterpillars, another option is to leave them on the milkweed itself. Using tomato cages and mosquito netting to cover plants can deter many pests. Do not use systemic fungicides, pesticides or herbicides in the area. Be very wary about what you spray. If you choose to bring your friends to a safe place, make sure it is well ventilated, and have enough milkweed to feed the voracious armies. Don’t forget to have plenty of nectar-rich flowers for your butterflies or any visiting monarchs to feed on. Butterflies require sunlight and plenty of nectar to keep them going, especially as they fly up to 25 miles a day in search of food. Aster, butterfly bush, echinacea, goldenrod, hyssop, lantana, rudbeckia, sunflower, western vervain, verbena, yarrow and zinnia all are butterfly favorites.

People of every age are inspired by the monarch. The best part about raising these critters is the reaction we get when people see this metamorphosis for the first time. Spreading knowledge is easy when people are moved by a miracle in motion. A majority of what is known about the monarch and its magnificent migration is documented and pursued by volunteers, or “citizen scientists.” It’s up to people like us. is a great resource for research and exploration. Let us know at Swede’s if you have any monarch sightings or have caterpillars that need a safe space to grow.

“The butterfly counts not months but moments, and has time enough.”

– Rabindranath Tagore

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