Alabama Butterfly Atlas

Silvery Blues have been occasionally recorded in the mountains of northeastern Alabama, though each observation has involved only a single individual. Never abundant, they are now regarded as rare or uncommon in Tennessee and North Carolina and may be extirpated in Georgia. Although Silvery Blues are clearly habitat specialists, the reasons for their scarcity remain unclear.

Their single annual flight coincides with the spring bloom of preferred host plant, Carolina Vetch, a small, delicate legume that occurs patchily in rocky woodlands and hardwood forests. Unlike the butterfly, Carolina Vetch is found throughout most of the state. Adults nectar on its flowers and lay eggs on its buds. Caterpillars feed on buds, flowers, and occasionally leaves, and are often attended by ants drawn to sugary secretions produced by specialized glands.

Nationwide, many Silvery Blue subspecies occur--at least two are found in the East. One northern subspecies has expanded its range southward presumably because it adapted to use Crown Vetch as a host. This introduced and invasive plant, widely used for erosion control, is common in pastures, roadsides, and abandoned fields. Whether Appalachian Silvery Blue populations will adapt to using Crown Vetch remains uncertain but seems unlikely. For now, they persist only in highly localized colonies associated with Carolina Vetch and are often absent even where the plant is plentiful. The best way to find Silvery Blues is to locate a thriving patch of Carolina Vetch in the mountains of northeastern Alabama and hope that, when it blooms in early spring, these small blue butterflies appear.