New Jersey Butterfly Club

Northern Metalmark

Calephelis borealis

Identification: Very small—about 1”. Above: FW and Hw dark brown with dull orange along outer wing margins and 2 concentric rows of shiny, silvery lines ("metal marks") near wing margins. Below: FW and HW bright yellow-orange with many dark, curved, concentric dashes and 2 shiny, silvery lines near wing margins. Does not resemble any other species in NJ—but be careful not to mistake it for a moth.

NJ Status and Distribution: Resident. Classified as Special Concern in NJ. Extremely rare and very local. Formerly occurred in many colonies between Branchville in Sussex County and Blairstown in Warren County. Now reduced to a just a few small colonies.

Habitat: Very closely associated with dense colonies of Roundleaf Ragwort, always under stands of Eastern Redcedar on limestone. Not found off limestone even where host plant occurs. Also requires nearby flowers for nectaring (see Comments) but unlikely to visit gardens, as it does not travel far from its food plant.

Flight Period: One brood from mid-June to early August. Extreme dates: 6/19—8/2.

Caterpillar Food Plants: Roundleaf Ragwort (Packera obovata [formerly Senecio obovatus]).

Overwintering Stage: Caterpillar.

Good Locations: None listed because of sensitivity.

Comments: The host plant is under duress from the rapid, and mostly unchecked, spread of alien invasive plants such as Japanese Stilt Grass, Japanese Barberry, Asiatic Bittersweet, and Autumn Olive; host plants are also are being shaded out by maturing stands of redcedar. Adult metalmarks nectar mainly at Oxeye Daisy, Butterfly Milkweed, and Blackeyed Susan. Without habitat management this species will soon disappear from NJ as it has done from other states.