San Bruno Mountain, near San Francisco California, is the home of three endangered butterflies: the Mission Blue Butterfly, the San Bruno Elfin Butterfly and the Callippe Silverspot Butterfly. All three are rare. They share four additional characteristics: they all live on San Bruno Mountain; they all have a special plant on which they lay their eggs; they have a one year lifespan, and they have short adult lives.
The Mission Blue Butterfly lays its eggs on lupine. Silver Bush (Lupinus albifrons) is the preferred lupine of the Mission Blue. Summer and Varied Lupine also have the chemical mesophyll which the larvae eat. The eggs hatch after about a week depending on temperature. The caterpillar larvae have four changes of skin called instars. After the first two instars, the caterpillar will stop eating and drinking and sleep and move under the plant during the very cold times of the winter. After this slowdown, they resume eating and drinking as their skin grows and changes. Ants protect larval instars three and four from predators. At the end of the fourth instar, the caterpillar forms a chrysalis by splitting its skin and turning upside down and spinning a thread around itself. It stays in their position for ten days. After the ten days, the adult butterfly emerges, but only lives at most ten days. During its short life, it lays eggs and the cycle repeats itself keeping the species alive. The Mission Blue is a small blue butterfly with a one-inch wingspan.
The San Bruno Elfin Butterfly lays its eggs on stonecrop a succulent (Sedum spathulifolium) that grows on the tops of mountains. The tiny reddish or yellow caterpillars begin their lives in February. They eat the leaves until the buds explode into yellow blossoms. Then, they eat the blossoms that provide them with protein. In late May or June, the caterpillar crawls beneath the plant and makes a chrysalis. There, it stays until the following February. The butterfly emerges as a small brown butterfly. Ants also protect this butterfly as it feeds on the stonecrop. Unlike the Mission Blue, lack of habitat does not threaten this butterfly. No one plans to develop San Bruno Mountain.
Callippe Silverspot Butterfly is different from the Mission Blue and Elfin Butterflies for a couple of reasons. The first is that it likes to wander and will fly up to three-quarters of a mile in such of its favorite host plant, California Golden Violet. It also is a larger butterfly compared to these two with a wingspan of two and a half inches. Like the Elfin Butterfly, the Callippe Silverspot spends most of its life underneath its host plant. Its mother lays her eggs there where the violet has dried out, usually in June. The eggs hatch out about one week later. They eat their shell and crawl back into the ground to await winter. Once the violet begins to bloom, the caterpillars emerge and eat the plant. They continue feeding into April when they become chrysalises. After two-weeks, they become adults and the males fly to the top of the mountain in search of a female. They mate and the female looks for dried out violets on which to lay her eggs. The process repeats itself.
Most butterflies share the same short lifespan. Most face threats due to development or habitat destruction. The best way to secure the survival of these beautiful and amazing creatures involves preserving those habitats and preventing the destruction of areas where butterflies frequent. Another strategy involves planting host plants to areas where butterflies live.
