Danaus plexippus plexippus

Monarch

In California, the monarch is best-known for its annual migration to the coastal groves where it roosts in clusters that have long been a tourist attraction. monarchs east of the Rockies migrate to and from roosting sites in Mexico. In our area, movement is generally northward towards Canada and back as temperatures allow (they don't do well in freezes). Where I live, freezes aren't an issue most years, and we may have monarchs all year. The larvae eat milkweed leaves and flowers, many of which contain toxins (cardenolides) that make most of the adult butterflies distasteful to predators. The bold coloration of the caterpillars advertises this toxicity to would-be predators.

This is an excellent butterfly to attract to a garden, simply by planting milkweed - Asclepias species - preferably a native. For California, good choices include fascicularis (narrow leaf milkweed, the best in my opinion), eriocarpa, and californica. I plant fascicularis in the garden every year now, and can't imagine not having at least a monarch or two present and lending the garden a more regal air. Non-native curassavica is widely available at nurseries, and it will attract monarchs even through the winter, but it should be avoided in our area. It's a good thing that native milkweed in your garden dies back part of the year, since this rids the area of plants infected with pathogens that afflict monarchs, in particular OE (Ophryocystis elektroscirrha), a protozoan whose spores accumulate on the plants.