New Jersey Butterflies

Compton Tortoiseshell

Nymphalis vau-album

Identification: Medium—2.6" (a little larger than Question Mark). Above: Black, orange and yellow. Single white spots on leading edges of FW and HW stand out. Below: FW and HW gray-brown with basal half of wings distinctly darker than the outer half.

NJ Status and Distribution: Resident. An uncommon, northern species that occurs as far south as northern Somerset and Hunterdon counties. Occurs only as a stray in central and southern counties. Most often reported from western Bergen County (Mahwah), west through northern Morris County (Kinnelon and Rockaway) and northern Passaic County (West Milford and Ringwood), to all of Sussex County and northern Warren County—basically the region north of Route 80.

NJ Range Map-Compton Tortoiseshell

Habitat: This is primarily a woodland species that seldom nectars. Most often seen on dirt roads or parking lots bordered by mature deciduous forest. Not a typical garden visitor. Sometimes seen nectaring in spring on the yellow flowers of willows (Salix).

Flight Period: March into November. Adults overwinter and generally emerge in March. The single new brood usually emerges in late June or early July and flies into November, with time out for aestivation in the latter half of summer. Peak flight time is in April-May, and July. Extreme dates: 2/26—12/13.

Larval Food Plants: Birches (Betula), poplars (Populus), and willows (Salix).

Overwintering Stage: Adult.

Best Locations: Unpaved roads in the Delaware Water Gap NRA; dirt parking lots and woods roads in Whittingham and Wildcat Ridge WMAs; Campgaw Mountain CR.

Comments: Populations fluctuate substantially. Recently, the best places to see this striking butterfly have been Wildcat Ridge WMA, and Mountain Road in the Delaware Water Gap NRA between Walpack Cemetery and Buttermilk Falls. Best bet is to walk or slowly drive this road (especially on a weekday when there is little or no traffic) watching very carefully for the sharp triangular profile of this species when its wings are closed. If lucky and persistent, you will find this beautiful butterfly among the more common Eastern Commas, Question Marks, and Mourning Cloaks. Flushed individuals often land head downward on nearby trees.

Compton Tortoiseshell

Walpack, Sussex Co., NJ, 7/3/07.

Compton Tortoiseshell

Wildcat Ridge WMA, Morris Co.,NJ, 6/30/06.

Trembling Aspen

Leaves of Trembling Aspen (Populus tremuloides). This upland tree is one of many host plants for Compton Tortoiseshell, Mourning Cloak, and Red-spotted Purple.