New Jersey Butterfly Club

Juniper Hairstreak

Callophrys gryneus

Identification: Very small—size of thumbnail. Almost never seen with wings open. Below: FW and HW bright green (when fresh) with bold white postmedian lines bordered with brown on inner side only. Outer 3 segments of FW postmedian band form a straight line. Appears quite brownish when heavily worn. Similar hairstreaks: NJ's only other green hairstreak is Hessel's, which may appear a bluer-green and has brown on both sides of the postmedian bands. Also, the last segment of Hessel’s FW postmedian band is displaced outwardly. Hessel's is generally confined to the immediate vicinity of southern NJ Atlantic White-cedar bogs, while Juniper is much more widely distributed in upland fields with Eastern Redcedar.

NJ Status and Distribution: Resident. Generally fairly common and widely distributed throughout.

Habitat: Open areas near host plant. May be attracted to gardens that are near stands of the host plant. Prefers to nectar at milkweeds and mountainmints.

Flight Period: Two broods from early April to mid-September, but mainly late April to late May, and early July to mid-August. Extreme dates: North Jersey 4/9-10/22; South Jersey 3/27-10/12.

Caterpillar Food Plants: Eastern Redcedar (Juniperus virginianus), a native evergreen tree of advanced upland successional fields/young forests.

Overwintering Stage: Pupa.

Good Locations: Sandy Hook NRA, Flatbrookville, White Lake Natural Resource Area, Woodbine RR tracks (Cape May Co.), Kimble’s Beach Rd. (Cape May NWR), Cape May Bird Observatory gardens in Goshen.

Comments: Some years, in North Jersey at least, the spring brood is small or absent.