The Oak Feeding Duskywings

In Nebraska there are three Duskywings whose larvae feed on oaks, these being Juvenal’s (Erynnis juvenalis), Horace’s (E. horatius) and Sleepy (E. brizo). Two, Juvenal’s and Sleepy, fly only in the spring while Horace’s has three flights – spring, mid and late summer. They rarely stray far from oak trees and so their distribution in the state largely matches that of native oaks. True to their name they are brown/black in color. Juvenal’s and Horace’s are medium sized while the Sleepy is about half their size. Juvenal’s and Horace’s Duskywings are extremely difficult to separate in the field with the best identifying mark being the presence of two lighter spots on the ventral hindwing (as indicated by the arrow).

Top – Juvenal’s Duskywing (Erynnis juvenalis) dorsal and ventral Bottom – Horace’s Duskywing (E. horatius) dorsal and side views
Sleepy Duskywing – Erynnis brizo

As mentioned earlier the distribution of these species is limited by the presence (or absence) of native oaks. Public access areas to see these butterflies (skippers actually – hooked antennae instead of clubbed) range from Indian Cave State Park, Twin Oaks SWMA and Table Rock SWMAs in the southeast up to the Niobrara Valley Preserve in the north central part of the state. Large portions of the state with oaks have no records for these three species so there are a lot of possibilities out there.

The season is moving along and I did not see any of these Duskywings on our earlier visit to Indian Cave State Park so another trip to southeast Nebraska is on my agenda next week when the weather warms up since two of these are spring fliers and I don’t want to miss them.

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