New Jersey Butterfly Club

A chapter of the North American Butterfly Association (NABA)

Sleepy Duskywing

Erynnis brizo

Identification: Very small—1.35" (between size of Dreamy and Juvenal’s Duskywings). Above: Male FW blackish-brown with no white spots or dots; a distinct dark-gray chainlike pattern extends across outer FW, and a less-distinct chain across the inner wing. Shows pale frosting around FW apex and leading edge but lacks well-defined silvery patch of Dreamy. Female has a similar pattern but ground color is browner, resulting in more contrast with the dark-gray chainlike marks; a pale brown patch along leading edge of wing between the 2 chainlike patterns is variably frosted. HW (blackish-brown in male, brown in female) has a row of small, pale spots along the edge and other pale spots scattered in the outer half. Below: Dark brown with many small, pale spots mirroring those on upperside. Other: Palps shorter than those of Dreamy Duskywing, but this is not always obvious. Other differences are that Sleepy is larger than Dreamy, lacks the white dot on FW, and has a less well-defined silver patch at bend of wing. Sleepy emerges earlier, so that when Dreamy reaches its peak, Sleepies are worn.

NJ Status and Distribution: Resident. Uncommon and local in North Jersey, but more common and widespread from Burlington and Monmouth counties south.

NJ Range Map-Sleepy Duskywing

Habitat: Dry woodland edges and openings. Also, ridgetops in Sussex and Warren counties where the host plant occurs.

Flight Period: One brood from mid-April to late May. Extreme dates: North Jersey 4/6—6/1; South Jersey 3/29—6/1.

Caterpillar Food Plants: Shrubby oaks such as Scrub Oak (Quercus ilicifolia) and Blackjack Oak (Q. marilandica), but possibly young specimens of other species of oaks.

Overwintering Stage: Caterpillar.

Good Locations: Thomas F. Breden Preserve at Milford Bluffs, Jenny Jump State Forest (Summit Trail), Delaware Water Gap NRA (Crater Lake Road and AT to Catfish Fire Tower), Peaslee WMA, Warren Grove RA, Woodbine RR/Bike Path.

Comments: Although this species partially overlaps in range and flight period with Dreamy Duskywing, seldom are both species seen together, as they frequent habitats with different caterpillar food plants. Dreamy and Sleepy Duskywings differ from Juvenal's, Horace's, and Wild Indigo in that they lack glassy FW spots.

Sleepy Duskywing

Male, Millbrook Gap, Warren Co., NJ, 5/8/05.

Sleepy Duskywing

Jenny Jump SF, Warren Co., NJ, 4/27/12.

Sleepy Duskywing

Bear Oak (Quercus ilicifolia), a shrubby oak of dry habitats that is the principal caterpillar food plant for Sleepy Duskywing in New Jersey.