Alternate Common Name: Tailed Blue.
This species is found east of the Rockies, from southern Canada to Central America. It may also occur in patches in the intermountain west and southwestern U.S. Eastern-tailed blues occur in isolated sections of northern and west central Idaho.
Adults occur in open areas, particularly those recently disturbed.
Caterpillars feed on the buds, flowers, seeds, and sometimes leaves of legumes, including
species of clover (Trifolium spp.), alfalfa (Medicago spp.), pea
(Lathyrus spp.), vetch (Vicia spp.), and bean (Phaseolus
Adult: Butterflies obtain nectar from relatively short plants with open, shallow flowers, such as wild strawberry (Fragaria spp.) and white sweet clover (Melilotus alba).
The caterpillar is equipped with a honey gland, also known as a dorsal nectary organ, which emits a sugary solution agreeable to ants. The ants feed on the solution and in turn protect the caterpillar from predators. Also for protection, the caterpillar bears a pair of everscible tubercles or tentacles on the eighth segment. These tubercles are usually housed within the body, but when the caterpillar feels threatened by the approach of a potential predator, they can be pushed out to release a chemical which mimics an ant alarm pheromone. This scent causes the ants to become frenzied and aggressive, and the potential predator takes leave or is eaten by the ants. Caterpillars overwinter within the pods of host plants in a physiological state called diapause, and pupate in the spring. Each year, there are three generations in the northern part of its range and many generations in the south; in the case of multiple generations during a given summer, only the caterpillars of the last generation overwinter. Each caterpillar undergoes four stages of growth, called instars. Adults generally fly from March to December. This is one of the few members of the family Lycaenidae that can be found resting with its wings open.
Males patrol near host plants for receptive females. Females lay eggs on flower buds and stems.
|Idaho Status:||Unprotected nongame species.|
|Global Rank:||G5; populations are widespread, abundant, and secure.|
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