Your garden can help monarch butterflies thrive

On this midwinter drizzly morning, Google has posted an animated drawing of a butterfly by artist Kevin Laughlin. The “Google doodle” calls attention to the anniversary of the incredible discovery of the “Mountain of Butterflies” in central Mexico.

The reserve, a World Heritage site, is the winter home to a majority of monarchs living in the eastern United States and Canada. Those living west of the Rocky Mountain range, “overwinter” along the California and Baja coast, our backyard.

This fascinating migration (a one-way trip south and a multigenerational journey north) was highlighted in the book “Flight Behavior” by Barbara Kingsolver. Kingsolver, who is appreciated for her wit and intellect, provides a fictional scenario; the logging of trees in the Mexican Sierra Madre mountain range, causing mudslides wiping out much of the habitat of the overwintering monarchs.

With its natural habitat demolished, the confused monarchs attempt to overwinter in the Appalachian Mountains on a farmer’s tree-covered hillside. The forest is about to be clear-cut. Kingsolver’s piece of entertaining and illuminating fiction makes us question and contemplate the creeping changes in our environment.

Most butterfly species transform from eggs to larvae to pupae to adults, never leaving the region of their host plant. The monarch butterfly is the only butterfly species known to make a two-way migration as part of its life cycle.

Monarchs cannot take cold weather. As winter approaches, they’ve learned to use air currents and thermals to travel as far as 3,000 miles to relax, mate, and rest up for a “relay race” migration in the spring.

The northern migration of monarchs involves several generations. Butterflies that have lived through the winter begin their journey. Along the way, they stop and lay eggs on the milkweed plant.

Eggs hatch, become larvae (caterpillars), pupate and transform into butterflies that continue on their way, seemingly knowing which direction to travel.

Last February, the U.S. Fish and Wildlife Service published a report on the disappearance of nearly 10 million monarchs since 1990. The decline in the monarch population is mostly attributed to the use of herbicides on milkweed (the food source of monarch larvae).

Our gardens here in Cambria can become an oasis for monarchs and other pollinators if we plant pollen plants as food source for mature butterflies, and native milkweed for larvae (caterpillars).

Milkweed: Native or Non-native?

Much of the monarchs’ food source is being destroyed by drought and spraying along roadways. Before you plant milkweed seeds or seedlings, know which variety is best to feed monarchs. There are varying opinions on this subject. Native milkweed is considered invasive in some areas. But contained in our gardens, native milkweed is not likely to present an “invasion” problem.

Some scientists recommend planting only native milkweed in California gardens, like Asclepias californica (California milkweed), Asclepias cordifolia (purple or heartleaf milkweed), Asclepias fascicularis (narrow-leaved milkweed), and Asclepias speciosa (showy milkweed). They believe exotic (non-native) milkweeds may cause some monarchs to loiter, avoid migrating and become infected with harmful parasites. Because non-native milkweeds are perennial and don’t die back, they tend to pass parasites on to monarchs more readily.

The loveliest of the California natives is showy milkweed (Asclepias speciosa). Its blossoms are carnation-scented, a rosy mauve. Monarchs, however, seem to prefer “showy’s” homelier stepsister, the narrow-leafed milkweed (fascicularis). Hide its rather plain looks behind native irises or shrubs.

If you have planted a non-native species of perennial milkweed and really want to keep it, cut it to the ground several times a year. This keeps it healthy and helps to kill the parasites that infect the monarch. “Going native”, of course, is always safer.

This story was originally published January 20, 2016 at 11:20 AM with the headline "Your garden can help monarch butterflies thrive."