Undersides of adult eastern tailed-blues are pale gray with numerous small dark spots. Both sides of the hindwings have 2 (occasionally 1 or 3) orange spots by the thin tail. Males are blue above, while the upper side of females is a mixture of blue and dark gray with blue predominant in the spring and dark gray predominant later.
Larvae are downy, green or brown, with a darker brown line along the top and oblique (slanted) brown lines along the sides, and with a small, black head.
Similar species: Azures and the other blues in Missouri do not have tails on the hindwings. Hairstreaks have hindwing tails, but they also have banding on the undersides of the wings.
Habitat and Conservation
The caterpillars are herbivores that graze on vegetation. They secrete a substance that is attractive to certain types of ants, and these ants help protect the larvae from predators.
The thin, antennae-like tails on the hindwings can fool potential predators, such as birds and jumping spiders, into snapping at the hindwings, which are less valuable to the butterfly than its head.