Hidden along the coast of Carpinteria stands a grove of eucalyptus trees that provide a sheltering winter home for monarch butterflies gathering from points throughout the western United States. Early in the morning, giant clusters of monarchs huddle together, hundreds or thousands softly fluttering, waiting for the air to warm their flight muscles. As the day’s warmth grows, butterflies open their wings, catching the rising thermals that send them aloft seeking food and mates.
The monarch butterfly life cycle is intimately linked to the seasons and landmarks of coastal California, where the entire Western monarch population over-winters in warm, sheltered spots. The lengthening days of spring trigger dispersal across the West, as far as the flanks of the western Rockies. Breeding adults are in search of their favored food plant, milkweed, to lay their eggs. Several generations hatch throughout spring and summer, until fall’s generation returns to the same grove where their ancestors spent last winter. No one yet knows how monarchs return to these ancestral sites. And we may never know, because monarch butterflies are experiencing a steep decline (99.4 percent since the 1980s) that may force their population below the number of individuals needed to maintain the species.
Monarchs suffer from the combined forces of habitat destruction, climate change, the disappearance of milkweed essential to their life cycle, and the widespread use of toxic pesticides and herbicides in agriculture and home settings. And while monarchs are a striking and beloved species whose habits and population numbers scientists are relatively well aware of, thousands more species of insects—microscopic, or less visually exciting, or with a smaller habitat range—are disappearing without recognition, in what one recent New York Times article calls the “Insect Apocalypse.”
Insects (as well as countless other invertebrate and vertebrate species) are facing challenges around the world, and in our backyards. Habitat destruction via development for housing and agriculture turns dense, vibrant ecosystems into ecologically bleak zones where only a few weedy and domesticated species thrive. Human-caused climate change furthers the disappearance of distinct ecological niches, the cradles of biodiversity. The widespread use of chemicals in our homes, businesses, and public spaces (which seep into our soil, air, and waterways) are detrimental to many life forms.
The disappearance of other-than-human species has greatly increased in the last few decades, such that scientists have termed this geological era the “Anthropocene,” in recognition of the outsized impact humans now have on earth processes. We are in the midst of the sixth great spasm of extinction to convulse the world thus far, and the first that is distinctly human-caused. The loss of species diminishes us all, creating a world that is less diverse, less robust, less complex and unique.
There are also very practical reasons for concern. Insects and other invertebrates are essential to all life as we know it. Insects are important decomposers and recyclers, turning dead plant and animal material into living soil upon which all life is based. According to the Xerces Society for Invertebrate Conservation, insect pollinators are necessary for the reproduction of over 85 percent of the world’s flowering plants, including more than two-thirds of the world’s food crop species. In the United States, the economic value of insect pollination is $3 billion per year.
The wild world also depends upon pollinators and other insects as “keystone species” binding whole ecosystems together. Insect pollination bears wild fruit and seed, the diet of approximately 25 percent of all birds as well as many mammals of all sizes. Insects themselves are also an important food source for birds and animals. The worldwide disappearance of insects is the beginning of an alarming cascade of species extinctions.
The challenges the natural world faces are great, almost overwhelming. It’s important to remember that the choices we make have an impact beyond our own lives, and there is much we can do. If you are able, support diverse, small-scale, organic agriculture with your purchasing power. Here in the Carpinteria Valley, we are lucky to be able to support our farmer-friends in growing year-round produce without the use of chemicals, and with wild edges of crop areas set aside for native pollinators.
Limit the use of chemicals in your home and landscape. Invertebrates are particularly sensitive to many chemicals. Even those not sold as “pesticides” can have detrimental effects on insect populations. Use preventative care, good garden timing, and organic treatments for the health of all your landscape.
Consider planting a biodiverse “pollinator garden,” with native plants blooming continuously throughout the growing season for shelter and forage for insects. Monarch butterflies need narrow-leaf milkweed (Asclepias fascicularis) to survive. Showier, non-native species, often planted with the best intentions, are actually detrimental to monarch health and reproduction. Tropical milkweed species do not die back in winter, allowing a toxic monarch parasite to persist on food plants, increasing the spread of the disease.
This is just one example of the importance of growing native species for native insects. Plant, insect, and animal species of our bioregion have evolved for millennia in complex interactions that we are wise to respect and rebuild. Creating a native plant garden, no matter how small the space, allows urban fragments for insect populations to survive. If you want to learn more about building a garden habitat from the ground up, the Carpinteria Garden Park and the Carpinteria Valley Water District are sponsoring a three-part “Grass to Garden” class series in March. For more information, visit the Garden Park’s web site.