Erynnis lacustra

Sleepy Duskywing

For a long time, I thought of the sleepy duskywing as rare, since I had seen it so rarely at Cactus Spring Trail (and nowhere else), a place I've gone to regularly for years. But to the west at Keen Camp Summit near Idyllwild, I found several in late April across several visits in 2021, and I've since learned it can be locally common. Identification is easy: they have irregular dark striping across the forewings but lack the light hyaline patches of the other duskywings. They fly in April and May in a single brood, and mature caterpillars overwinter in a shelter made of oak leaves. In the spring, they pupate and again emerge in April.

Sleepy Duskywing - Erynnis lacustra
Sleepy duskywing, Erynnis lacustra, at Cactus Springs Trail in the Santa Rosa Wilderness, March 30, 2011.
Sleepy Duskywing - Erynnis lacustra
This one was along Keen Camp Summit Road in the San Jacintos near Idyllwild. April 28, 2021.
Sleepy Duskywing - Erynnis lacustra
Ventral view of Erynnis lacustra, Cactus Springs Trail, April 15, 2011.
Sleepy Duskywing - Erynnis lacustra ovipositing
Sleepy duskywing, Erynnis lacustra, ovipositing on host desert scrub oak along the Cactus Springs Trail, same day as above ...
Egg of Sleepy Duskywing - Erynnis brizo lacustra
... and this is the resulting egg.
Caterpillar of Sleepy Duskywing - Erynnis lacustra
Nine years later, I was checking a scrub oak along Cactus Spring Trail and found two leaves fastened together with silk. This lacustra caterpillar was inside. June 30, 2020.

©Dennis Walker