Here's a super-common butterfly - the Variable Checkerspot. Also known as the Chalcedon Checkerspot, the Variable Checkerspot is more commonly seen on Mount Diablo right now as a caterpillar. The caterpillars are black, with orange markings, which warn potential predators that they taste bitter due to the iridoid glcosides they accumulate from the plants they eat. 

Caterpillars can be seen now feeding on the leaves, flowers and bracts of Indian Paintbrush, Monkey Flower, 

Penstemon, Plectritis, California Figwort (aka California Beeplant, aka Scrophularia californica) and many other plants. When they reach full size, they drop off into the leaf litter, or under fallen limbs or rocks, and pupate. They will emerge as adults the following Spring. There is one generation of butterflies per year.

Why are they called Variable Checkerspots? The adult comes in many shades, with the top of the forewing colored with a mix of black, orange, or brown, with a mix of yellow, red, or white spots, or some combination of some or all those colors (see the difference in the 2 adults shown here). The smaller male butterflies show mostly in April – June and patrol constantly for the larger females.

Soon they will be one of the most common butterflies seen on our hikes/rides. But see the caterpillars now!