Complete Guide To The Eastern Tailed-Blue Butterfly
The Eastern Tailed-Blue butterfly (Everes comyntas) is small, gorgeous, abundant throughout North Carolina, and amazingly easy to overlook.
This tiny gossamer wing butterfly has a wingspan of only about an inch. It flies low to the ground and folds its wings tightly over its back when perched. This hides the beautiful, iridescent blue of its wings.
You have to really pay attention to see all the beauty this butterfly has to offer.
But this tiny species is well worth the effort to observe in the wild. One thing I’ve always appreciated about this species is the length of the adult’s flight season. Eastern Tailed-Blue butterflies appear early in the spring and survive into the fall. So, they show off their beauty much longer than some of the other larger, flashier butterfly species.
Fun facts about Eastern Tailed-Blue Butterflies
- The Eastern Tailed-Blue butterfly (Everes comyntas) is names for a thin, delicate tail that trails off each hind wing.
- Tails may be short or missing on older individuals. The tails are fragile and easily rubbed off or torn due to normal wear and tear or during predator attacks.
- Eastern Tailed-Blue butterflies have bright orange marks on their hind wings, right at the base of their tails, that contrast sharply with the silvery-gray of their underwings.
- Some scientists propose that the combination of the tail and the orange spots is an anti-predator defense. The idea is that they mimic the insects’ head and antennae, which tricks predators into attacking the wrong end of the butterflies.
Classification
| Kingdom | Animalia |
| Phylum | Arthropoda |
| Class | Insecta |
| Order | Lepidoptera |
| Family | Lycaenidae (“gossamer wings”, sub-family Polyommatinae, “blues”) |
| Genus species | Everes comyntas |
How do I know I’m looking at an Eastern Tailed-Blue Butterfly?
Appearance of Eastern Tailed-Blue Butterfly eggs
The eggs of Eastern Tailed-Blue butterflies are pale green. Females lay them one at a time on flowers, buds, and leaves of pea plants in family Fabaceae.
Appearance of Eastern Tailed-Blue Butterfly caterpillars / larvae
Eastern Tailed-Blue caterpillars grow to about 0.5 inches (1.25mm).
Their color varies widely and can be green, yellow, pink, rose, or purple-brown (Wagner, 2005), but are usually dark green. A thin reddish-brown center stripe runs down the length of their backs and a pale white and red stripe runs down their sides. Short hairs cover the caterpillars’ bodies. Usually these hairs are white, but can sometimes be black (Wagner, 2005).
Chrysalids of Eastern Tailed-Blue butterflies are buff-colored (Pyle, 1981).
Appearance of adult Eastern Tailed-Blue Butterflies
Adult Eastern Tailed-Blue butterflies grow to about 1.1 inches (2.8 cm).
They have furry bodies, which vary in color depending on sex. The fur of male Tailed-Blues is bright blue above and white below, while the fur on females is brown above and white below. Both sexes have black eyes and black and white-striped clubbed antennae.
The sexual dimorphism between male and female Eastern Tailed-Blues seen in the body fur carries over into the appearance of the upper surface of their wings. Males are much more brightly colored than females. Their dorsal wing surfaces are brilliant, iridescent blue overall, with wide black bands along the outer margins. A thick fringe of short white hairs surround both sets of wings.
Females are mainly brown on top; what blue coloration they have appears only when light strikes their wings at certain angles. Spring-flying females have more blue at their wing bases than do adult females seen later in the season.
The underside, or ventral, wing surface of these butterflies is pale silvery-white with curved rows of distinct black spots outlined in white. Two orange marks appear side by side on the hind wing margins. One of the orange marks is at the base of a fine, hairlike tail trailing from the edge of each hind wing.
Only two species of butterfly have this threadlike tail; Eastern Tailed-Blues (Everes comyntas) and its close relative the Western Tailed-Blue (Everes amyntula).
Tips for identifying Eastern Tailed-Blue Butterflies in the field
The best way to identify Eastern Tailed-Blue Butterflies in the field is by the color pattern on the ventral wing surface.
These butterflies close their wings over their backs when perched. They show their bright blue upper wing surface only when basking in the sun and when in flight. They flutter their wings rapidly and fly quickly so casual observers usually see only brief flashes of brilliant color.
The presence of tails on the hind wings isn’t the most reliable field mark. Eastern Tailed-Blue Butterfly tails are thin and fragile. They sometimes break off or wear away as a result of the insects brushing against vegetation or predator attacks.
Why have wing tails at all?
Some believe that the combined wing “tails” and bright, high-contract orange marks is an anti-predator defense, in that it mimics the insect’s head and antennae and tempts predators into attacking the wrong end of the butterfly.
I personally am unsure how effective an anti-predator strategy this actually is.
The hind wing spots and tail do attract attention, but Eastern Tailed-Blue Butterflies also have large, black eyes that are very obvious against their pale body fur.
To my eyes, the butterflies’ eyes and antennae look much bigger than the hind wing spots and tails. I don’t find it hard to figure out which end is which. I’m not sure a predator would be fooled. After all, the predator’s life depends on getting it right.
Also, the tails are very short compared to the butterflies’ actual antennae and don’t move as much. I don’t think a predator would tricked.
However, this is not to say that this hypothesis is wrong; only that it doesn’t make intuitive sense to me.
When can I find Eastern Tailed-Blue Butterflies?
Eastern Tailed-Blue Butterflies (Everes comyntas) have three broods per year in North Carolina, starting in February and extending through to November (Opler and Malikul, 1992). Females lay their eggs in flower buds and stems of host plants, while the caterpillars overwinter inside bean and pea pods (Pyle, 1981).
Where should I look to find Eastern Tailed -Blue Butterflies?
Look for adult Eastern Tailed-Blue Butterflies in open, sunny areas with low-growing vegetation, like meadows, fields, and overgrown lawns. They are also common in disturbed areas like power line cuts and along railroads.
These butterflies like to fly low, almost hugging the ground. They can be hard to see when perched because of their small size and relatively inconspicuous ventral wing surface coloration.
The best way to spot these butterflies is to wait motionless in a likely habitat, like a flowery meadow, and watch carefully for flitting motion inches above the tops of the plants. Don’t get distracted when you see one. Follow it down into the vegetation with your eyes until it lands and you can watch it unfurl its long, thin proboscis and feed.
Male Eastern Tailed-Blue Butterflies also like to gather around damp soil to drink salts and other minerals. This behavior is called “puddling” and it’s a common behavior among many species of butterfly, especially in the spring. Lucky observers can sometimes see many Eastern Tailed-Blue butterflies puddling together.
What do Eastern Tailed-Blue Butterflies eat?
Larval food plants
Eastern Tailed-Blue caterpillars eat plants in the legume and pea family, such as clovers (Trifolium), beans (Phaseolus), wild peas (Lathyrus), lupine, vetch, and trefoils (Desmodium) (Bartlett-Wright, 1993) (Pyle, 1981). They eat all parts of the plant, including flowers and seeds as well as new leaves.
Adult butterfly food
Adult Eastern Tailed-Blue butterflies feed on nectar from a wide variety of flowering plants, especially white sweet clover, dogbane, butterfly milkweed, and daisy fleabane.
Where to go from here
Join the conversation! Please share your experiences, knowledge, or observations in the comments.
References
Bartlett–Wright, Amy. 1993. Peterson First Field Guides: Caterpillars. Boston, MA: Houghton Mifflin Company.
Opler, Paul A. and Malikul, Vichai. 1992. Peterson Field Guides: Eastern Butterflies. New York, NY: Houghton Mifflin Company.
Pyle, Robert Michael. 1981. National Audubon Society Field Guides to Butterflies: North America. New York, NY: Alfred A. Knopf.
Wagner, David L. 2005. Princeton Field Guides: Caterpillars of Eastern North America. Princeton, NJ: Princeton University Press.
