New Jersey Butterflies

Oak Hairstreak

Satyrium favonius

Identification: Very small—size of thumbnail. Almost never seen with wings open. Below: FW and HW gray-brown with narrow, black-and-white postmedian bands that on HW form an "M" near the tails. Orange spot near tails touches the margin but not the "M" mark. Similar hairstreaks: White M Hairstreak is grayer below, has a small white dot near leading edge of HW (usually missing in Oak), has a larger orange spot that touches the "M" but not the margin, and is brilliant blue above (visible in flight). Gray Hairstreak is gray below (but may appear brown when heavily worn), the postmedian bands include orange, the orange spot at HW tails is larger, and usually has a thin black line across the inner side.

NJ Status and Distribution: Resident. Widespread but generally rare. More frequently reported from southern counties. Most reports are of single individuals.

NJ Range Map-Oak Hairstreak

Habitat: Forest edges and openings with food plants.

Flight Period: Mid-June to mid-July. Extreme dates: North Jersey 6/14—7/16; South Jersey 6/1—6/26.

Larval Food Plants: Oaks (Quercus spp.) in the White Oak group.

Overwintering Stage: Egg.

Best Locations: Greenwood Forest WMA, Pomona area.

Comments: Even active field observers fail to find this goodie most years. Any observations (preferably documented with photos) of this rare butterfly should be reported to the NABA-North Jersey Butterfly Club.

Oak Hairstreak

Colliers Mills WMA, Ocean Co., NJ, 6/10/12, on Indianhemp.