North American Range
The smallest blue in Vermont, with tiny threadlike tails and a silvery hindwing fringe, is among most beautiful. Common throughout the eastern United States. While perched, these butterflies rub their hindwings together to create a distraction with their tails. Males patrol near hostplants during the day. Females lay eggs on flower buds and caterpillars eat buds, flowers, and seeds. Larvae overwinter, pupating the following spring. Although most Lycaenids do not perch with open wings, Eastern Tailed Blue sometimes bask with their wings at a 45 degree angle. Adults nectar but have a very short proboscises and are limited to nectaring from flowers close to the ground which are open and short tubed.
One narrow tail on hindwing. Upperside of male iridescent blue; summer females uniformly brown, spring females smaller with much blue at the wing bases. Underside of hindwing pale gray with black bar at the end of the cell, distinct black spots, and three large orange spots at outer margin near tail.
Probably three flights: early May through early June, mid July through late July, and mid August through into October. Extreme dates: 4 May 2007 in Dorset (R. Stewart), 13 October 2003 in Grand Isle (D. Hoag).
Distribution and Habitat
Scudder (1889) wrote “found throughout New England even in the White Mountain district and is everywhere a common insect, especially in the southern half”. This largely remains true. Both historically and during VBS, Eastern Tailed Blue was commonly found throughout Vermont; with fewer records in Northeastern Highlands and the northern portions of Green Mountains and the Northern Piedmont. They are adaptive generalists and are able to utilize a wide array of open habitats, including disturbed areas. Caterpillar hosts include Yellow Sweet Clover (Melilotus officinalis), Alfalfa (Medicago sativa), clover (Trifolium), and others. Adults nectar at Yellow Sweet Clover (Melilotus officinalis), asters (Aster), cinquefoil (Potentilla) and other short-tubed flowers.