New York Natural Heritage Program
Frosted Elfin
Callophrys irus (Godart, [1824])

Identifying Characteristics [-]
This species is identifiable with any recent butterfly book. It is a rather large, very gray elfin, closely associated with lupine or wild indigo.

Characters Most Useful for Identification [-]
In the field, association with the foodplant is the first clue to the identity of this species. The combination of extensive gray beneath, tailed hindwing, and the relatively large size for an elfin are generally diagnostic for adults.

Best Life Stage for Proper Identification [-]
The best life stage for identification is the adult stage, although the larvae are identifiable by experts.

Behavior [-]
This species is almost always found within 50 feet of one of the foodplants.

Diet [-]
The laval foodplant is Wild Indigo (Baptisia spp.) in some southeastern New York colonies and Wild Lupine (Lupinus perennis) elsewhere in the state. Both plants are used on Long Island, but no colony has been found to use both plants anywhere in the range of the species.
Frosted Elfin Images
click to enlarge
The Best Time to See
There is one annual generation with adults starting about late April to mid-May and often persisting into June. Wild Indigo (Baptisia spp.) feeders probably occur a bit later than lupine feeders in similar climates. At least with the Baptisia feeder, adult emergence is staggered and some fresh individuals can be seen for approximately one month. The egg stage is brief and the larval stage lasts for about a month, depending on the weather. Most larvae pupate by the end of June and most of the year is spent in that stage.
Reproducing Larvae present and active Pupae or prepupae present
The time of year you would expect to find Frosted Elfin reproducing (blue shading), larvae present and active (green shading) and pupae or prepupae present (orange shading) in New York.
Similar Species
  • Hoary Elfin (Callophrys polios)
    Hoary elfin lacks tails and is unlikely to be found in Frosted Elfin habitats.
  • Henry's Elfin (Callophrys henrici)
    Henry's Elfin is slightly smaller, much browner beneath and usually perches high.