Microtia (Dymasia) dymas imperialis

Tiny Checkerspot

Tiny checkerspots are butterflies of our southern deserts found in close association with their host plant from the Acanthaceae family, chuperosa (Justicia californica). That desert shrub grows in dry or rocky soils and thrives in desert washes, such as at Plum Canyon and Hellhole Canyon in Anza-Borrego Desert State Park. If it is doing well thanks to good desert precipitation, the butterfly can do well or even explode in numbers. In late September, 2023, many thousands of this species were swarming Plum Canyon when I visited. In dry years, this butterfly can be absent or nearly so. So in terms of the timing of adult flights, it depends on the timing and amount of precipitation, but generally there is an early brood around March to May, and a late brood in September-October.

While hummingbirds attend to the red chuperosa flowers and pollinate them, the tiny checkerspots flutter around and in the leafy shrub. Females oviposit in clusters on the underside of leaves. Young larvae emerge several days later and feed on the green leaf surface, leaving tell-tale damage behind. Mature caterpillars can chew through the leaf. They will pupate on the plant or not too far away. Adults also visit flowers nearby, often asters, and seem to particularly love sweetbush flowers.