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New Jersey Endangered and Threatened Species Field Guide
Species Group: Invertebrate
State: Special Concern
The hoary elfin is a small butterfly that has an orange brown upperside and a brown underside. Their forewing and outer margin are white with a frosted appearance. The bottom half of the hind wing is a pale, frosted gray. This species’ wingspan ranges from ¾ of an inch to 1 inch. During the larval period, hoary elfins are yellow green to blend in with new growth of the host species. As the new growth ages, the caterpillars fade to dark green for better camouflage.
There are several other butterflies that this particular species can be confused with. Their name “hoary” refers to the grayish-white shading along the outer edge of their forewing. This shading is much more extensive in the hoary elfin than it is in other species.
DISTRIBUTION AND HABITAT
Hoary elfins have a widespread population. They range from eastern Alaska south through Canada and then spread out west into the Rockies and east into the Appalachians. They have fairly significant gaps in their range. They are considered to be very local in the northeast from Maine to New Jersey. New Jersey is likely the southernmost edge of the hoary elfin’s range as they have been extirpated from Pennsylvania and West Virginia and are considered extremely rare in Maryland and Virginia.
This species prefers mixed hardwood forests, rocky or sandy barrens, and bogs that are abundant with their host species, bearberry. Females are thought to be more widely dispersed while males keep within a defined distance of perching areas.
Adult hoary elfins feed on the nectar of a variety of flowers. Typically they prefer bearberry, but they are also found feeding on leatherleaf, pyxie, wild strawberry, blueberry, and willow. The larvae feed exclusively on bearberry. They feed on the buds and flowers of the bearberry.
Males will perch on plants in sunny clearings and in low areas to look for females. Eggs are greenish white in color and are laid singly on leaf buds or flowers. Larvae can be found on bearberry plants. When in chrysalid form, the hoary elfin is hibernating. When they emerge, they have one flight period from April to June.
CURRENT STATUS, THREATS, AND CONSERVATION
In New Jersey, the hoary elfin is listed as a species of Special Concern. They have shown a significant decline in the eastern part of their range. This is likely due to the rise of development and the decline of suitable habitat. It is also thought that global warming is taking a toll on the hoary elfin and is perhaps a contributing factor in their decline. Although they are under threat in New Jersey and most of the northeast, the western population is fairly stable. Therefore, the hoary elfin is not listed at the federal level.
In 2015, the New Jersey Endangered and Nongame Advisory Committee recommended changing this species' status from Special Concern to Threatened within the state, but no formal rule proposal has been filed to date.
HOW TO HELP
The Endangered and Nongame Species Program would like for individuals to report their sightings of hoary elfins. Record the date, time, location, and condition of the animal and submit the information by submitting a Sighting Report Form. The information will be entered into the state’s natural heritage program, commonly referred to as Biotics. Biologists map the sighting and the resulting maps “allow state, county, municipal, and private agencies to identify important wildlife habitats and protect them in a variety of ways. This information is used to regulate land-use within the state and assists in preserving endangered and threatened species habitat remaining in New Jersey.”
Text written by Emily Heiser in 2011 and updated by Mike Davenport in 2016.
Species: C. polios
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