''Celastrina idella'', the American holly azure, is a species of butterfly of the family Lycaenidae. It is found on the east coast of the United States.

Description

Adults

The wing uppersides are uniform light blue or purplish-blue, shinier in females than in males, with white fringes. The wing undersides are light gray or white with dull black spots.

Larvae

Caterpillars vary in color between green and white. Some caterpillars develop white chevron markings on their back.

Differences from similar species

American holly azures differ from the co-occurring azure species by their smaller size, wing color, flight period, pupal diapause, and larval hosts.

Northern azure ''Celastrina lucia'', the lucia azure, northern azure, eastern spring azure or northern spring azure, is a species of butterfly of the family Lycaenidae. It is found eastern North America, ranging from the Maritimes south through the Appalachia ...

s have earlier flight and pupal periods, larger size, and more vivid adult and larval color.

Spring azure ''Celastrina ladon'', the spring azure or echo blue, is a butterfly of the family Lycaenidae. It is found in North America from Alaska and Canada south of the tundra, through most of the United States except the Texas coast, southern plain and ...

s can be distinguished by close examination of the wing scale structure in a captured individual but are otherwise nearly indistinguishable by sight. The spring flight of

summer azure ''Celastrina neglecta'', the summer azure, is a butterfly of the family Lycaenidae. It is found in North America. Layberry, Hall, and Lafontaine, in ''The Butterflies of Canada'', describe the species: The upper surface is pale blue with an ext ...

associates with black cherry and does not diapause before the summer flight, which begins after the end of the American holly azure flight.

Appalachian azure The Appalachian azure (''Celastrina neglectamajor'') is a butterfly in the gossamer wings family Lycaenidae. The male is light blue on the upperwing with a narrow, dark line running along the edge of the forewing. The underwing is chalky white an ...

s and

cherry gall azure ''Celastrina serotina'', the cherry gall azure, is a butterfly of the family Lycaenidae. It is found across North America as far north as the treeline. Its flight time is between mid-May and mid-June in eastern Ontario after the spring azure and ...

s have ranges west of the range of American holly azures.

Range

The species' occurrence range extends along the Atlantic coastal plain of the United States, from New Jersey to Georgia.

Life cycle

The species has one flight per year in the spring, between the flight periods of the

northern azure ''Celastrina lucia'', the lucia azure, northern azure, eastern spring azure or northern spring azure, is a species of butterfly of the family Lycaenidae. It is found eastern North America, ranging from the Maritimes south through the Appalachia ...

and the spring brood of

but overlapping with

spring azure ''Celastrina ladon'', the spring azure or echo blue, is a butterfly of the family Lycaenidae. It is found in North America from Alaska and Canada south of the tundra, through most of the United States except the Texas coast, southern plain and ...

and

. The flight is from late April to late May in the northern part of the range.

Adults

Adults emerge to begin their single flight in spring, after remaining in the pupal stage during summer, autumn, winter, and early spring.

Eggs

Adults lay white eggs on buds of holly flowers.

Larvae

Caterpillars hatch and bore into the buds in late spring. Worker ants of a few species, including the ferruginous carpenter ant (''

Camponotus chromaiodes ''Camponotus chromaiodes'', known generally as, the ferruginous carpenter ant or red carpenter ant, is a species of ant in the family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recogni ...

''), an unnamed carpenter ant '' Camponotus nearcticus'', and an unnamed citronella ant ''

Lasius alienus ''Lasius alienus'', or cornfield ant, is a species of ant in the subfamily Formicinae (family Formicidae). Workers have a length of about 2–4 mm, Queens are larger (7–9 mm). Distribution They live in Europe, from Spain to the Cauca ...

'', accompany the caterpillars.

Pupae

Caterpillars become light brown pupae in late spring or early summer. The pupae undergo diapause until spring.

Food

Adult nectar sources

Adults take nectar from highbush blueberry ('' Vaccinium corymbosum''), sand myrtle (''

Kalmia buxifolia ''Kalmia buxifolia'' is a species of flowering plant in the family Ericaceae known by the common name sandmyrtle, or sand-myrtle. It is native to the mid-Atlantic and southeastern United States, where it has a disjunct distribution, occurring in ...

''), chokeberries (''

Aronia arbutifolia ''Aronia arbutifolia'', called the red chokeberry, is a North American species of shrubs in the rose family. It is native to eastern Canada and to the eastern and central United States, from eastern Texas to Nova Scotia inland to Ontario, Ohio, Ke ...

'' and ''

Aronia melanocarpa ''Aronia melanocarpa'', called the black chokeberry, is a species of shrubs in the rose family native to eastern North America, ranging from Canada to the central United States, from Newfoundland west to Ontario and Minnesota, south as far as Ark ...

''), black cherry (''

Prunus serotina ''Prunus serotina'', commonly called black cherry,World Economic Plants: A Standard Reference, Second Edition'. CRC Press; 19 April 2016. . p. 833–. wild black cherry, rum cherry, or mountain black cherry, is a deciduous tree or shrub of the g ...

''), red maple ('' Acer rubrum''), and

rock cress Rockcress is a common name used for several similar genera of flowering plants in the family Brassicaceae: *'' Arabis'', with primarily Old World species *''Arabidopsis ''Arabidopsis'' (rockcress) is a genus in the family Brassicaceae. They ar ...

('' Arabis'' sp.).

Larval host plants

Caterpillars eat the flowering parts of male plants of four species of holly: American holly ('' Ilex opaca''),

inkberry Inkberry is a common name for several unrelated plants: * Any plant in the genus ''Phytolacca'' (pokeweeds) ** Especially '' Phytolacca americana'' (American pokeweed) * ''Dianella nigra'' (''turutu'' in Māori, New Zealand blueberry) * '' Ilex gla ...

('' Ilex glabra''),

smooth winterberry ''Ilex laevigata'' (Pursh) A. Gray, commonly referred to as smooth winterberry, is a plant species in the Aquifoliaceae (holly family). It is native to the eastern coastal United States. References laevigata Trees of Northern America

('' Ilex laevigata''), and Yaupon holly ('' Ilex vomitoria''). Two possible alternative host plants are tall gallberry holly ('' Ilex coriacea'') and

Virginia willow ''Itea virginica'', commonly known as Virginia willow or Virginia sweetspire, is a small North American flowering shrub that grows in low-lying woods and wetland margins. Virginia willow is a member of the Iteaceae family, and native to the southe ...

(''

Itea virginica ''Itea virginica'', commonly known as Virginia willow or Virginia sweetspire, is a small North American flowering shrub that grows in low-lying woods and wetland margins. Virginia willow is a member of the Iteaceae family, and native to the southe ...

'').

Evolution and taxonomy

American holly azures co-occur with closely related azure species but differ in their host plant adaptation.

Sympatric speciation Sympatric speciation is the evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region. In evolutionary biology and biogeography, sympatric and sympatry are terms referring to organi ...

may have occurred due to host plant specialization, i.e., different populations of azures may have genetically diverged once some populations adapted to a single host not used by other populations.

References

{{Taxonbar, from=Q20686174 Celastrina Butterflies of North America Butterflies described in 1999