New Jersey Butterflies

Frosted Elfin

Callophrys irus

Identification: Very small—size of thumbnail. Almost never seen with wings open. Below: FW and HW rather uniform reddish-brown with irregular dark postmedian lines. HW with whitish frosting on most of outer portion and usually with a small but distinct dark spot near the short, rounded tails. Similar hairstreaks: On Hoary Elfin entire outer portion of HW is frosted, and FW has a narrow frosted area as well as a thin, white postmedian line. Hoary lacks the dark spot on HW. Henry’s Elfin has marked contrast between light and dark brown areas, has small white marks at ends of median separation lines, and lacks dark spot near HW tails.

NJ Status and Distribution: Resident. Classified as Threatened in NJ. Now found only in a few colonies in Cape May, Cumberland, and Atlantic counties. A small colony persisted at the Assunpink WMA, western Monmouth County, until 2003.

NJ Range Map-Frosted Elfin

Habitat: Open areas, including glades within forests, in close proximity to the host plant.

Flight Period: Mid-April into June. Extreme dates: South Jersey: 3/22—6/15.

Larval Food Plants: Wild Indigo (Baptisia tinctoria), which is a native perennial of open, often disturbed, habitats, and Wild Lupine (Lupinus perrenis) another native that grows on loose, well-drained soils. Current populations in South Jersey apparently use only Wild Indigo, and it is unknown whether former populations in North Jersey used Wild Lupine.

Overwintering Stage: Pupa.

Best Locations: None listed because of sensitivity.

Comments: Nectars mostly early in the morning and perhaps late in the day on various heath-family shrubs. Retreats to glades within woodlands at night and during windy or otherwise inclement weather. The presence of these protected areas may be an important habitat requirement.

It will be interesting to see whether this species expands north into its former range in North Jersey, where both food plants also grow, since it has recently become more common in Massachusetts.

Frosted Elfin

Atlantic Co., NJ, 5/1/03.