New York Natural Heritage Program
Karner Blue
Plebejus melissa samuelis (Nabokov, 1944)
Insects

General Description [-]
A small, sivery blue butterfly with orange crescents on the margins of the underside of the wings. The dorsal surface of the male is all violet-blue, as compared to the dorsal surface of the female, which is dull purplish-blue near the body and turning a dull brown away from the body. The dorsal surface of the lower wings also have orange crescents along their bottom edges.

Characters Most Useful for Identification [-]
The combination of marginal orange spots on the underside of all wings and lack of tails on the hindwings is diagnostic. The males have no orange at all above. The females have some orange on the hindwing above and, unlike the Eastern Tailed-blue (Cupido (Everes) comyntas), always have some blue near the body on upper side of all wings. Both sexes are also larger than tailed blues. Azures and silvery blues have no orange on any surface.

Best Life Stage for Proper Identification [-]
The adult is the best life stage for identification. The larvae can be identified by an expert, but both Frosted Elfin (Callophrys irus) and Eastern Tailed-blue [Cupido (Everes) comyntas] larvae occur on lupine and are similar. The eggs can also be identified, but in part this involves context and experts.

Behavior [-]
It is unlikely to be seen more than a few yards from patches of lupine (Lupinus perennis), although wandering individuals do occur up to a mile or more away from main breeding areas.

Diet [-]
Larvae feed only on the native lupine (Lupinus perennis) in nature. The adults take nectar from many kinds of low growing flowers, native or otherwise.
Karner Blue Images
click to enlarge
The Best Time to See
The exact phenology varies from year to year and colony to colony. Those in the most open habitats tend to be about a week ahead of those in more wooded places. There are always two annual generations. The eggs overwinter and hatch, but not all at once, around the middle of April. The larvae mature mostly in late May and pupate. Adults emerge in late May to early June and are active for two to three weeks. The eggs from these adults hatch in a few days and the larvae are mostly mature in early July. Second brood adults fly for about three weeks and peak numbers usually occur for about a week in the second half of July. The eggs laid by these adults hatch the following spring.
J F M A M J J A S O N D
Reproducing Larvae present and active Eggs present outside adult Pupae or prepupae present
The time of year you would expect to find Karner Blue reproducing (red shading), larvae present and active (blue shading), eggs present outside adult (green shading) and pupae or prepupae present (orange shading) in New York.
Similar Species
  • Eastern Tailed-Blue (Everes comyntas)
  • Spring Azure (Celastrina ladon)