Monarchs. Photo: Margo Bars

We were high school students hiking up open, cross-country terrain, passing mariposa lilies and heading toward an unnamed pass. We hoped to get a view of Lake Tahoe from the top. We began seeing a few butterflies here and there, but weren’t ready for what we saw next. The butterflies became thicker and took a narrower path as they approached the pass. At the top they were going over the pass in an area about 12 feet wide and 10 feet high like they were going through a tunnel with invisible sides. If we stood in the middle of the “tunnel,” butterflies bounced off us or even landed on us. Butterfly experts tell me these thousands might have been painted ladies. On other occasions, on still, warm days in the Sierra Nevada, by wet meadows with lots of daisy family annuals, I have been rewarded by seeing a variety of butterflies. While these days were uncommon, the migration over the pass was unique in my experience.

Butterfly gardening is not always easy. In our history of gardening for butterflies at the UC Santa Cruz Arboretum, perhaps we can say the butterflies made the first overture. True, the first Arboretum plantings were a group of various eucalyptus species. But monarch butterflies found our grove probably on a side trip from the local Natural Bridges population. Later we received donor support and encouragement to increase our commitment to butterflies. Then we received a special endowment to always keep butterfly gardening in our plans. We have used some of this funding to propagate and plant numerous native buckwheats, Lessingia filaginifolia, Lotus scoparius, Keckiella, Ceanothus thyrsiflorus, C. arboreus, yarrow, Coreopsis, Encelia, Ericameria ericoides, Aster, madrone, Erigeron glaucus, and Mimulus (for the caterpillars).

Roses don’t blow away when it’s windy and hummingbirds are still out in a light rain, but butterflies present some challenges. Hummingbirds are easier because all you have to do is provide them some nectar-producing plants that they can get their beaks into. Butterflies, on the other hand, are most easily seen on warm still days. They need some nearby water with a place to land and drink. No one would think of going into a garden to try to rid it of all the baby hummingbirds, but what do most people do when they see caterpillars? Some take out the “diseased” plant and never plant that kind again, or spray it with chemicals. Some people just prune off the caterpillar-ravaged branches and throw them in the trash. To be a “good gardener” you rake up the debris in your garden. To be a good butterfly gardener, you leave some of the dead leaves and debris because you know there are some caterpillars or larvae in the duff. As one butterfly enthusiast said, “If you don’t provide homes for the larval stages [caterpillars and larvae], then when you plant flowers all you are doing is stealing someone else’s butterflies.” With short lifespans for many species of butterflies, you must visit your garden often to see most of the visitors each year.

So leave those caterpillar-eaten shrubs in the garden, leave some of the leaves and debris about the garden, and try to figure out which of your native “weeds” might actually be host plants for some butterflies’ caterpillars. Some bad weeds are good for caterpillars or as nectar plants, but these can be replaced by natives or non-weedy non-native plants. If you have no ponds (in a sunny spot), add an artificial pond made from a shallow saucer. To be useful it must have pebbles, sand, or mud for butterflies to land upon. One could also use coarse sand or gravel next to the water instead of pebbles. Don’t forget to change the water often enough not to encourage mosquitoes. Provide a bit of shelter from the wind and a sunny spot. Plant lots of flowers that have landing platforms, like members of the sunflower, buckwheat, and verbena families, and then wait for a warm, still summer day and you’ll probably have butterflies.