Eastern Tailed Blue: Essential Facts and Fascinating Insights

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The Eastern Tailed-Blue butterfly is a charming, tiny creature that graces various habitats with its delicate presence. Found in fields, pastures, roadsides, and other open, sunny areas, it is the most commonly encountered blue butterfly in regions like Alabama, where it is the only tailed blue species. With several generations occurring throughout the season, their population continues to grow and thrive as summer progresses.

Adult Eastern Tailed-Blues have pale gray undersides adorned with numerous small dark spots. Their hindwings feature two, and occasionally one or three, orange spots near the thin tail. Males stand out with their vibrant blue upper sides, while females showcase a mixture of blue and dark gray, with blue being dominant in spring and dark gray taking over later on. These captivating butterflies are an important part of our ecosystem, and their presence enhances the natural beauty of any environment they inhabit.

Eastern Tailed-Blue Overview

Scientific Classification

The Eastern Tailed-Blue butterfly, also known as Cupido comyntas, is a part of the Lycaenidae family.

Physical Characteristics

Eastern Tailed-Blue butterflies are small in size, with wingspans typically ranging from 0.75 to 1.25 inches.


  • Males: Iridescent blue on the upper side of the wings
  • Females: A mixture of blue and dark gray, with blue more predominant in the spring and dark gray later in the season

The underside of the wings is pale gray, adorned with numerous small dark spots. Both sides of the hindwings display 2 (occasionally 1 or 3) orange spots by the thin tail.

Here is a brief comparison of Eastern Tailed-Blue and other small butterflies:

Feature Eastern Tailed-Blue Other Small Butterflies
Wingspan 0.75 to 1.25 inches Varying
Underside Wing Pattern Pale gray, dark spots Varying
Hindwing Orange Spots 1 to 3 Varying
Trailing Tail Thin Varying

The trailing tail of the Eastern Tailed-Blue is a thin and delicate feature, which distinguishes it from other small butterflies. This tail, coupled with its unique coloration and markings, make it a remarkable species in the world of butterflies.

Habitat and Distribution


The Eastern Tailed-Blue is a butterfly species commonly found throughout North America, extending from Canada to Central America. Some specific regions where this butterfly thrives include the Eastern United States, Washington, California, Texas, New Hampshire, and even parts of Mexico1.

Common Habitats

Eastern Tailed-Blues prefer open, sunny spaces. Key habitats where these butterflies can be found are:

  • Fields: Both cultivated and wild fields are attractive to Eastern Tailed-Blues, as they often have an abundance of flowers and host plants2.
  • Roadsides: These butterflies frequent roadside vegetation, taking advantage of the sun and the plentiful nectar sources3.
  • Meadows: Grassy areas with flowers provide the perfect environment for Eastern Tailed-Blues to feed and lay eggs4.

In conclusion, Eastern Tailed-Blue butterflies have a wide distribution across North and Central America, with a strong presence in the United States and Canada. They commonly inhabit open spaces like fields, roadsides, and meadows and are easily identifiable by their blue color and distinctive tails.

Life Cycle

Eggs and Caterpillars

  • Eastern Tailed-Blue butterflies lay their eggs on host plants like wild peas and clover.
  • Eggs are usually round and pale green.

Caterpillars hatch from the eggs and are either green or brown in color. They have downy bodies and a darker brown line that runs down their sides. Examples of host plants that caterpillars feed on include:

  • Wild peas
  • Clover
  • Alfalfa

Pupa and Adult Butterfly

Eastern Tailed-Blue caterpillars transform into pupae after completing their growth. Pupae are:

  • Brown
  • Well camouflaged
  • May be attached to the host plant or found in nearby debris

After completing the pupal stage, adult Eastern Tailed-Blue butterflies emerge. Males have blue wings, while females have a mix of blue and dark gray.

Generations and Broods

Eastern Tailed-Blue butterflies have multiple generations each year. The number of generations can vary depending on the location and conditions.

Spring Brood: Typically emerges in May.

Summer Brood: May overlap with the spring brood, appears from July through September.

Spring Brood Summer Brood
Emergence May July through September
Key Characteristics Males predominantly blue, females with more blue on the upper side of wings Males predominantly blue, females with more dark gray on the upper side of wings

In summary, the Eastern Tailed Blue has a life cycle that consists of eggs laid on host plants, caterpillars that feed on these host plants, pupae that transform into adult butterflies, and multiple broods of adults that emerge each year. The adult butterflies differ in wing appearance between males and females and between broods, with the spring brood having more blue in the female wings compared to the summer brood.

Diet and Feeding Habits

Floral Preferences

The Eastern Tailed Blue butterfly primarily feeds on nectar from various plants and flowers. Some of their favorite flowers to draw nectar from include:

  • Asters
  • Wild strawberry
  • Winter cress
  • Cow vetch
  • Wild pea
  • White clover
  • Cinquefoils
  • Shepherd’s needle

Eastern Tailed Blues also visit other flowers like bean, vetches, and alfalfa to supplement their diet.

Caterpillar Host Plants

Eastern Tailed Blue caterpillars feed on host plants, which typically belong to the legume family. Some of their preferred host plants include:

  • Bean
  • Vetches
  • Alfalfa
  • Wild pea

Comparison Table

Attribute Nectar Source Host Plants
Plant Categories Flowers Legumes
Examples Asters, White clover, Winter cress Bean, Wild pea, Alfalfa

Eastern Tailed Blues exhibit a diverse diet depending on their life stage, with adult butterflies relying on flower nectar, while their caterpillars consume host plants from the legume family.

Behavior and Interactions

Mating and Reproduction

  • Males are blue, while females have a mixture of blue and dark gray
  • Mating increases during summer months

Eastern Tailed-Blues exhibit unique mating behaviors. Males are a vivid blue color, whereas females display a mixture of blue and dark gray, with the blue being more predominant in the spring and dark gray later on. Mating activity tends to increase as the summer progresses and temperatures rise.

Ant Symbiosis

  • Larvae may attract ants through their honeydew secretions
  • Ants protect larvae from potential predators

An interesting aspect of Eastern Tailed-Blue’s lifecycle is its relationship with ants. It has been suggested that the butterfly’s larvae produce honeydew secretions, which attract ants. In return for the sweet treat, ants provide protection to the vulnerable larvae against potential predators.

Predators and Threats

  • Predators include birds, spiders, and other insects
  • Sightings in yards, gardens, ponds, and streams are common

As with many butterfly species, Eastern Tailed-Blues have their share of natural predators. These include birds, spiders, and other insects. Despite these threats, Eastern Tailed-Blue sightings are common in yards, gardens, ponds, and streams, showcasing their ability to thrive in various environments.

Comparison between males and females

Feature Male Female
Wing color Blue Mixture of blue and dark gray
Predominance Less visible in early summer More visible as summer progresses
Presence near Yards, gardens, ponds, and streams Yards, gardens, ponds, and streams

Overall, Eastern Tailed-Blues display fascinating behaviors and interactions within their environment, as well as with other species. They contribute to a diverse ecosystem and can often be spotted in a variety of habitats.

Conservation and Human Impact

Endangered Species Act Status

The Eastern Tailed-Blue (ETB) butterfly is not currently listed under the Endangered Species Act (ESA). This small butterfly, belonging to the Lepidoptera order and the family Lycaenidae, is quite common in the U.S., thriving in various habitats such as meadows, fields, and along wooded edges.

Importance in Ecosystem

Eastern Tailed-Blues play a vital role in the ecosystem. Here are some key characteristics of their importance:

  • Pollination: Like other butterflies, ETBs act as pollinators, helping in the reproduction of various plants.
  • Prey: ETB larvae and adults serve as a food source for birds, spiders, and other insect predators in the ecosystem.
  • Indicator species: Changes in ETB populations can serve as early-warning signs for detecting shifts in ecosystem health.

Comparison of Eastern Tailed-Blue and Other Lycaenidae Butterflies

Feature Eastern Tailed-Blue Other Lycaenidae Butterflies
Size Small (wingspan of 0.75-1.25 inches) Varies (small to medium-sized)
Color Males: Blue above, pale gray with dark spots below; Females: A mixture of blue and dark gray Varies (sometimes brightly colored)
Tails Two thin tails (occasionally one or three) on hindwings Presence or absence of tails
Habitat Meadows, fields, wooded edges Wide variety, including forested areas, grasslands, and wetlands

In conclusion, although the Eastern Tailed-Blue butterfly is not listed under the ESA, it serves crucial roles in the ecosystem. Conservation efforts should continue to protect their habitats and overall well-being for maintaining a healthy, balanced ecosystem.

Creating a Butterfly-friendly Environment

To create a butterfly-friendly environment for Eastern Tailed Blue butterflies, focus on providing suitable host plants and flowers. Here are some important features to consider:

  • Host plants: Caterpillars need specific plants to feed on. Eastern Tailed Blue caterpillars prefer clover, which is found in areas like Jefferson and Waits.
  • Flowers: Adult butterflies feed on nectar from a variety of flowers. Selecting flowers that are native to your area will be beneficial to local butterfly populations.

Remember to group flowers of similar colors, as this can attract more butterflies. In addition to hosting plants and flowers, consider these aspects:

  • Zones: Be mindful of which plants are suitable for your local climate zone, as this can impact the butterflies’ ability to thrive.
  • Puddles or damp areas: Providing shallow puddles or damp areas can help attract groups of certain butterflies, as they need water to survive.

Avoid using broad-spectrum pesticides, as these can harm butterflies and their caterpillars. Instead, opt for organic methods to deal with pests. Now let’s compare the pros and cons of creating a butterfly-friendly environment:

Pros Cons
Attracts beautiful butterflies May require more upkeep
Promotes biodiversity Potential for some plant damage from caterpillars
Encourages pollination Limited to specific host plants and flowers

By following these tips, you can create a welcoming environment for Eastern Tailed Blue butterflies and enjoy the beauty they bring to your garden.

Fun Facts and Observations

Eastern Tailed-Blue butterflies can be easily spotted due to their distinct appearance. Some interesting features include:

  • Pale gray undersides with numerous small dark spots.
  • Males have blue upper sides, while females have a mix of blue and dark gray.
  • Both sides of the hindwings usually have 2 orange spots near the tail but may have 1 or 3 occasionally.

Eastern Tailed-Blues are commonly found in fields, pastures, roadsides, and other open, sunny areas throughout places like Alabama. These butterflies are known for their unique tails, which differentiate them from other Blue species.

As they are small and delicate creatures, Eastern Tailed-Blues are not suitable pets. However, observing them in their natural habitat is a delightful activity for nature enthusiasts. They can often be seen close to the ground, making it easy for people to appreciate their beautiful details.

Eastern Tailed-Blues aren’t the only species of butterflies with interesting features. Comparing them with another species, for example, Monarch butterflies, can be insightful:

Feature Eastern Tailed-Blue Monarch Butterfly
Size Small (15-25 mm wingspan) Large (93-105 mm wingspan)
Color Blue, gray, and orange spots Bright orange-black pattern
Habitat Open, sunny areas Meadows, fields, marshes
Tails Present Absent

In summary, the Eastern Tailed-Blue butterflies are fascinating creatures with unique features, such as their distinct orange spots, tails, and gender-based color differences. Though they are not pets, they can provide natural beauty and enjoyment when observed in open, sunny areas.


  1. Alabama Butterfly Atlas

  2. Missouri Department of Conservation

  3. Alabama Butterfly Atlas

  4. Missouri Department of Conservation

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Male (and subsequent female) Eastern Tailed Blue


Hairstreaks and Blues
Location:  Mayfield, KY
August 1, 2010 11:43 am
I have been photographing many butterflies this summer. I bought a book on butterflies and moths. The pictures in the book are all illistrations which makes some identifications difficult. I have pictures of both hairstreaks and I believe the Eastern Tailed-Blue. (also how do you tell the difference between the female eastern tailed-blue and the gray hairstreak?… my book shows them both marked almost exactly the same.) I am sending the photo I have of what I believe is the Eastern Tailed-Blue. I would like to tag my album accurately, so please correct me if I am wrong. I still have a couple butterflies unidentified. Maybe I can send them in for your help later.
Janet Fox

Male Eastern Tailed Blue

Hi Janet,
The proper identification of the Gossamer Winged Butterflies in the family Lycaenidae, including the Hairstreaks and Blues, can be a daunting task, but we agree that this is a male Eastern Tailed Blue,
Cupido comyntas.  According to BugGuide:  “male’s wings above iridescent pale blue with brownish-gray along outer margin; forewings with a short oblique black bar near middle; hindwings with a row of submarginal black spots and a small orange spot at the base of each projecting tail. Female’s wings larger with longer tails, gray above on body and wings, 2 or 3 small orange spots with black dots near margin of hindwings. Wings of both sexes below silvery gray with small dark spots and a few orange spots near margin of hindwings. That written description fits this image of a male Eastern Tailed Blue posted to BugGuide, but your specimen has two orange spots on the upper side of the lower wing near the tails.  It seems there is a degree or variability, since another image posted to BugGuide has two spots like your individual.  Your photograph has captured the butterfly in the process of puddling, taking fluids and minerals from a damp spot on the ground, and you can see the extended proboscis in your photograph.  For a good guide book with photographs is Jeffrey Glassberg’s Butterflies Through Binoculars series, broken up into two volumes for east and west.

August 3, 2010
Thanks for the fast response.  I have attached a pic of the other one. I am thinking it is the female eastern tailed-blue.  My book doesn’t show the gray hairstreak well, so I am not sure which one it is.
Thanks again for the help.
Janet Fox
Mayfield, KY

Female Eastern Tailed Blue

Hi again Janet,
We didn’t notice until today that you wrote back with a photo of a female Eastern Tailed Blue.  We are adding it to your original posting.

Letter 2 – Eastern Tailed Blue


eastern tailed blue
Hi. I just wanted to share a photo of what I believe is an eastern tailed blue, probably a male. We live near Ottawa, ON. Take care.
Hammond, ON

Hi Sharon,
Thanks for sending in your photo of an Eastern Tailed Blue, Everes comyntas.

Letter 3 – Eastern Tailed Blue


pretty little blue butterfly.
sorry i forgot to attach the photo. this butterfly was found in Cades Cove here in east Tennessee. I think its one of the blues but im not sure. i would love to identify the species. anyway hope you enjoy the photo. i love your website.
Michael D.

Hi Michael,
This sure looks to us like an Eastern Tailed Blue, Cupido comyntas.

Letter 4 – Eastern Tailed Blue


Eastern Tailed Blue
Hey Bugman,
Wanted to say again how much I enjoy your web site. I just love looking at other people’s photos; especially of butterflies. I managed to see and photograph one of these little tiny butterflies today. I believe it is an "Eastern Tailed Blue." I know that others have photographed this butterfly and the blue is more brilliant at times on the male than this picture. I wonder if it is the sunlight that tends to wash the color out? I would have liked to photograph this one on an overcast day or in filtered sunlight. I believe the blue color would be more brilliant. It it is still a very pretty butterfly. I believe someone from Ontario, Canada sent one in and you have it posted. This one was taken on 4/29/08 here in Charlotte, NC. Just thought you might like to see another one. Thanks,
Patrick Crone

Hi again Patrick,
You are doing a pretty good job of adding to our butterfly archive with your Eastern Tailed Blue, Cupido comyntas. The angle of the light is probably the most critical factor in the blueness of the wings. BugGuide notes that “Unlike most butterflies, this species has thrived where its habitat has been encroached upon by human activities. It is common along freshly mowed roadsides, flying to puddles. Many adults lose their tails. “

Letter 5 – Eastern Tailed Blue


Eastern Tailed Blue
Good evening Mr. Bugman,
I just discovered your site today, and as an inveterate 1. namer, 2. shutterbug (didn’t find that one on your site) and especially 3. macro fiend I was more than delighted! I’ve already ID’d several ‘bugs’ that had been bugging me. Thank you so much. I’ve attached 5 photos – 4 I know, and one I’d like to confirm. I live in Orange County, VIRGINIA – the north central piedmont of the state. All photos have been taken within a 4 mile radius of Orange, VA (county seat). If you don’t object, I’ll send others of insects you don’t appear to have – and maybe a few that I need help with. I just don’t want to overdo it in my enthusiasm for your site. What a great service, and I’ll add that no insects are harmed in the photographic process. They are either in the wild or occasionally found deceased, although no deceased ones in this group. Eastern tailed blue (Everes comyntas) – sitting on a blade of grass (June 2005) Thanks again for the wonderful site!
Best regards,
Orange, VA

Hi Lynne,
We are overwhelmed by all the images you sent in. In the future, please send only one image or one species per letter. It makes our lives so much easier. Thanks so much for expressing your enthusiasm. The Lycaean Blues, like this Eastern Tailed Blue, were among the butterflies written about by our favorite novelist, Vladimir Nabokov.

Letter 6 – Mating Eastern Tailed Blues


Subject:  mating Eastern Tailed-Blue Butterflies
Geographic location of the bug:  Occoquan NWR (Woodbridge, Va.)
Date: 09/07/2018
Time: 08:22 AM EDT
Your letter to the bugman:  Hi Daniel,
I recently was lucky enough to see Eastern Tailed-Blue Butterflies and a pair of Thread-waisted Wasps mating, at Occoquan NWR (Woodbridge, Va.) on September 7th and Huntley Meadows Park (Fairfax, Va) yesterday, respectively, and I thought you might enjoy seeing the images. You are welcome to post these if you like, of course.
Best Wishes,
Mating Eastern Tailed Blues

Your images are lovely.  Please resubmit using our standard submission form at the Ask WTB? link on our site:  ask-whats-that-bug/
Please limit submissions to a single species per form unless there is a good reason, like a predator/prey relationship.

Letter 7 – Possibly Eastern Tailed Blue


Subject:  Mystery butterfly
Geographic location of the bug:  Albany Pine Bush, Albany, NY
Date: 07/15/2020
Time: 11:13 PM EDT
Your letter to the bugman:  Dear Bugman,
Dispatch No. 3 from the Albany Pine Bush, with a real stumper (to me at least). Since you were so delighted with my Karner Blue butterflies a couple months ago, you’ll be happy to hear the second generation is now on the wing and the place is lousy with them. Everywhere you look, there is that flutter of blue (and sometimes they even hold still for us photographers!)
But Karner blues are old hat–this year I’ve been collecting hairstreaks. In addition to the Gray Hairstreak, which I’ve seen before, I’ve seen several Banded Hairstreaks and Coral Hairstreaks, new to me this year! Which leads me to my mystery: I stooped to photograph a butterfly a good distance away on a bush, and realized that although it looks like a hairstreak (and is about the same size), its markings don’t match anything in my field guide. (Naturally it disappeared before I could get any closer; the weird and rare ones never let me get a good photo, though as a rule I have found that hairstreaks are pretty patient about having a camera shoved in their face.)
For context, this was in an open area, gently sloping up from the trail, full of spotted knapweed, New Jersey tea (both very popular), and various other low grasses and bushes. There were a few other hairstreaks in the area, and a ton of Karner blues.
Any idea who my mystery hairstreak(?) was?
P.S. I’d be glad to send you photos of my other finds, if you’d like!
How you want your letter signed:  Susan B.

Possibly Eastern Tailed Blue

Hi Susan,
Have you entertained the possibility that this might be an Eastern Tailed Blue which is pictured on BugGuide.  That is our best guess at this time.

Letter 8 – Puddling Eastern Tailed Blues


Subject: Grey hairstreaks puddling
Location: Baltimore Maryland
July 19, 2014 1:33 pm
While out walking in my local park I came across a puddle where some Grey hairstreak male butterflies had gathered and wanted to share the picture with you guys 🙂
Signature: R.W

Puddling Eastern Tailed Blues
Puddling Eastern Tailed Blues

Dear R.W.,
Your image of puddling Gossamer Winged Butterflies is quite beautiful, however we would like to correct your identification.  We believe these are Eastern Tailed Blues,
Cupido comyntas, not Gray Hairstreaks.  Compare the markings on the images of Eastern Tailed Blues on BugGuide to the images of Gray Hairstreaks on BugGuide, and we believe you will agree with our correction.

I do agree and thank you for the correction, I was going vaguely based on memory of past books I’ve borrowed from the library- I wish you guys the best and have a safe summer.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

    View all posts
  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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Tags: Eastern Tailed Blue Butterfly

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