''Celastrina idella'', the American holly azure, is a species of

butterfly Butterflies are insects in the macrolepidopteran clade Rhopalocera from the Order (biology), order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The ...

of the family

Lycaenidae Lycaenidae is the second-largest family of butterflies (behind Nymphalidae, brush-footed butterflies), with over 6,000 species worldwide, whose members are also called gossamer-winged butterflies. They constitute about 30% of the known butterfl ...

. 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 azures 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 ''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 ...

and does not diapause before the summer flight, which begins after the end of the American holly azure flight. Appalachian azures and cherry gall azures 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 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 cherry gall azure. 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''), an unnamed carpenter ant ''

Camponotus nearcticus ''Camponotus nearcticus'', commonly named smaller carpenter ant is a relatively small carpenter ant. Its appearance is similar of that to ''Lasius niger'', commonly named the black garden ant. The ant is a household pest. Identification Workers ...

'', 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 In animal dormancy, diapause is the delay in development in response to regular and recurring periods of adverse environmental conditions.Tauber, M.J., Tauber, C.A., Masaki, S. (1986) ''Seasonal Adaptations of Insects''. Oxford University Press It ...

until spring.

Food

Adult nectar sources

Adults take nectar from

highbush blueberry Blueberries are a widely distributed and widespread group of perennial flowering plants with blue or purple berries. They are classified in the section ''Cyanococcus'' within the genus ''Vaccinium''. ''Vaccinium'' also includes cranberries, bi ...

(''

Vaccinium corymbosum ''Vaccinium corymbosum'', the northern highbush blueberry, is a North American species of blueberry which has become a food crop of significant economic importance. It is native to eastern Canada and the eastern and southern United States, from ...

''),

sand myrtle ''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 ...

('' Kalmia buxifolia''),

chokeberries ''Aronia'' is a genus of deciduous shrubs, the chokeberries, in the family Rosaceae native to eastern North America and most commonly found in wet woods and swamps. The genus Aronia is considered to have 3 species. The most common and wide ...

(''

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 ...

''),

(''

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'', the red maple, also known as swamp maple, water maple, or soft maple, is one of the most common and widespread deciduous trees of eastern and central North America. The U.S. Forest Service recognizes it as the most abundant nativ ...

(''

Acer rubrum ''Acer rubrum'', the red maple, also known as swamp maple, water maple, or soft maple, is one of the most common and widespread deciduous trees of eastern and central North America. The U.S. Forest Service recognizes it as the most abundant nati ...

''), and

rock cress Rockcress is a common name used for several similar genus, genera of flowering plants in the family Brassicaceae: *''Arabis'', with primarily Old World species *''Arabidopsis'', with primarily European species *''Boechera'', with primarily North Am ...

(''

Arabis ''Arabis'' ,''Sunset Western Garden Book,'' 1995:606–607 or rockcress, is a genus of flowering plants, within the family Brassicaceae. Description The species are herbaceous, annual or perennial plants, growing to 10–80 cm tall, usu ...

'' sp.).

Larval host plants

Caterpillars eat the flowering parts of male plants of four species of holly:

American holly ''Ilex opaca'', the American holly, is a species of holly, native to the eastern and south-central United States, from coastal Massachusetts south to central Florida, and west to southeastern Missouri and eastern Texas. Description ''Ilex opaca ...

(''

Ilex opaca ''Ilex opaca'', the American holly, is a species of holly, native to the eastern and south-central United States, from coastal Massachusetts south to central Florida, and west to southeastern Missouri and eastern Texas. Description ''Ilex opaca ...

''), inkberry (''

Ilex glabra ''Ilex glabra'', also known as Appalachian tea, dye-leaves, evergreen winterberry, gallberry, and inkberry, is a species of evergreen holly native to the coastal plain of eastern North America, from coastal Nova Scotia to Florida and west to Lo ...

''), smooth winterberry ('' Ilex laevigata''), and

Yaupon holly ''Ilex vomitoria'', commonly known as yaupon () or yaupon holly, is a species of holly that is native to southeastern North America. The word ''yaupon'' was derived from the Catawban ''yą́pą'', from ''yą-'' tree + ''pą'' leaf. Another com ...

(''

Ilex vomitoria ''Ilex vomitoria'', commonly known as yaupon () or yaupon holly, is a species of holly that is native to southeastern North America. The word ''yaupon'' was derived from the Catawban ''yą́pą'', from ''yą-'' tree + ''pą'' leaf. Another comm ...

''). Two possible alternative host plants are tall gallberry holly (''

Ilex coriacea Ilex coriacea, sometimes known as large gallberry or sweet gallberry, is a shrub in the Holly family native to coastal areas in the United States from Virginia to Texas. It exists primarily as an understory plant in pine forests, and is some ...

'') and Virginia willow (''

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