[Note: Verdance clients originally received this article in May, as part of our free monthly newsletter on gardens and gardening. To subscribe to the newsletter yourself, please register at our site.]
Recently I read that the number of monarch butterflies migrating from North America down to Mexico has fallen an astonishing 75% -- even after 75% of their population already was lost to a freeze on their overwintering habitat in 2002. At this rate, monarch extinction seems likely in years, not decades or centuries, raising the gloomy prospect of a future when our children or grandchildren never get to delight in these winged jewels.
Studies of why butterfly populations are declining indicate a complex web of causes including deforestation, climate change, and pesticides. Whatever the reasons, though, we each can still do small things to slow the decline.
The best way to attract adult butterflies is to plant a garden that includes the vital milkweed plus sunflowers, zinnias, marigolds, phlox, petunias, butterfly bush, black-eyed susans, lilies, cosmos and daisies. Even without such an intensive habitat in our yard, most of us can integrate a few of these plants -- and collectively create a butterfly garden that spans acres.
It's also important to encourage butterfly caterpillars. The Sunset Western Garden Book lists plants whose foliage is good caterpillar food; there is a broad palette to choose from (broccoli -- who knew?), and it's easy to tuck a few into any garden. If you would like suggestions on butterfly plants whose foliage or flowers will complement your existing landscape, it would be my pleasure to help.
Perhaps the most important step you can take is to avoid using pesticides -- even "natural" ones such as Bacillus thurigenesis (B.t.) -- that kill indiscriminately. Always try the most benign and pest-specific solutions first: for instance, a sharp jet of water knocks aphids off of leaves and flower buds, and non-toxic oils of neem, garlic, mint or clove discourage ants, mosquitoes, leafhoppers and thrips.
And above all, appreciate the graceful acrobatics and fragile beauty of every monarch, anise swallowtail, and mourning cloak you see. Currently a spectacular migration of painted ladies is making its way through the Bay Area; taking the time to notice them will create a warm place in your heart that will endure long after the last butterfly has fluttered by.
[Update: there are quite a few swallowtails floating around, and on 6/10 my client in Berkeley reported, "Amazingly we have hundreds of Monarchs hanging out in our neighborhood this year. First time we have seen it since we have lived here. Has lasted three days so far. Kind of cool."]