Wild Facts About The Gray Hairstreak Butterfly
Gray Hairstreak Butterfly Photo Gallery
Gray Hairstreak Butterfly. Strymon melinus. Photograph taken and design created by the author. Copyright © 2025 Now I Wonder. All rights reserved.
Gray Hairstreak Butterfly. Strymon melinus. Photograph taken and design created by the author. Copyright © 2025 Now I Wonder. All rights reserved.
Gray Hairstreak Butterfly. Strymon melinus. Photograph taken and design created by the author. Copyright © 2025 Now I Wonder. All rights reserved.
Gray Hairstreak Butterfly. Strymon melinus. Photograph taken and design created by the author. Copyright © 2025 Now I Wonder. All rights reserved.
Gray Hairstreak Butterfly. Strymon melinus. Photograph taken and design created by the author. Copyright © 2025 Now I Wonder. All rights reserved.
Diagram of a Gray Hairstreak Butterfly labelled with identifying field marks. Strymon melinus. Photograph taken and design created by the author. Copyright © 2025 Now I Wonder. All rights reserved.
How To Identify Gray Hairstreak Butterflies
Adult Butterflies
- Gray Hairstreak butterflies have:
- Dark gray wings above with a single orange and black spot in each hind wing border,
- The gray can look quite blue at certain angles and in certain light.
- Pale gray wings below decorated with a single, jagged black and white line, sometimes edged in orange,
- Two long, thin tails on each hind wing
- Dark gray wings above with a single orange and black spot in each hind wing border,
- Both sexes look similar.
Caterpillars
- The larval form of Gray Hairstreak butterflies are usually light green and covered with short bristles.
- Sometimes, the caterpillars can be red, brown, or pink (Wagner 2005).
- Gray Hairstreak caterpillars can look a lot like those of the Eastern Tailed Blue butterfly (Cupido comyntas), which is a related butterfly in the Gossamer-Winged Butterfly family Lycaenidae.
How To Find Gray Hairstreak Butterflies
- Of all the Hairstreak butterfly species found in the eastern United States, the Gray Hairstreak is the most common.
- Look for these butterflies on flowers in open areas with lots of sunshine, such as:
- Meadows,
- Along roadsides,
- In old fields,
- Home gardens,
- Utility easements.
- Caterpillars feed on many different plants including:
- Pea family plants (Fabaceae) like Hog Peanut (Amphicarpaea bracteata), Spurred Butterfly Pea (Centrosema virginianum), and clovers (Trifolium spp.)
- Mallow family plants (Malvaceae) like Crimson-Eyed Rosemallow (Hibiscus moscheutos).
Changing Strategies For Changing Times
- Like many butterfly species, male Gray Hairstreak butterflies are territorial.
- But unlike some other species, Gray Hairstreaks use two different strategies to defend their territories and switch between them depending on how many rival males encroach.
- One study found that when the number of encroaching males was fairly small, individual male Gray Hairstreaks repelled intruders from their perch trees.
- But when the number of intruders increased, the perched males switched to patrolling the area around their perch trees (Alcock and O’Neill 1986, https://doi.org/10.1111/j.1469-7998.1986.tb03568.x).
Sorting Out The Gossamer-Wings
- Despite being classified in different genera, Gray Hairstreak butterflies can be mistaken for another gossamer-winged butterfly, the Eastern Tailed Blue (Cupido comyntas) at first glance.
Under Wing Comparison
- The underside (ventral) surface of the wings of both species are mostly pale silver-gray and decorated with small black markings.
- But the black markings on Gray Hairstreaks are arranged in a single, zig-zag row, sometimes edged with orange on the edge closest to the wing bases.
- The Eastern Tailed Blue’s black markings are outlined in white and scattered across the wing surface instead of a single, distinct row.
- But the black markings on Gray Hairstreaks are arranged in a single, zig-zag row, sometimes edged with orange on the edge closest to the wing bases.
- Both species also sport at least one prominent orange and black spot along the trailing edge of each hind wing.
- Gray Hairstreaks have only one orange-capped black spot and it tends to be larger than those of the Eastern Tailed Blue butterfly.
- Eastern Tailed Blues can have two orange and black spots.
Upper Wing Comparison
- The upper (dorsal) wing surface of both male and female Gray Hairstreak butterflies is dark gray overall.
- Unlike the vibrantly blue males, female Eastern Tailed Blue butterflies are also gray, although paler and more brown than Gray Hairstreaks.
- Both species sport an orange-capped black spot in the border of each hind wing and have tails on their hind wings.
- Gray Hairstreak butterflies have two tails,
- Eastern Tailed Blue butterflies have only one on each hind wing.
My Nature Journal Sightings
09/13/2025
Today brought another new species sighting!
When I first spotted this tiny gray butterfly flitting around the flowering bushes that grew alongside the trail, I assumed it was an Eastern Tailed Blue Butterfly (Cupido comyntas).
The size was about right. This butterfly kept its wings folded over its back as it crawled across the flowers and showed only the gray undersides, and Eastern Tailed Blues are extremely common.
As the saying goes, “if you hear hoofbeats, think horse, not zebra”.
And yet. Something didn’t add up. As I watched it for a few minutes, I started to notice tiny differences between the butterfly before me and the field marks that say “Eastern Tailed Blue Butterfly”.
First, the orange spot on the underside of its wings looked bigger and much brighter than those I’ve seen on Eastern Tailed Blues.
Second, the black spots on this butterfly formed a solid, zig-zag line rather than a soft curve of rounded dots.
And third, as the butterfly moved in and out of the sun, it dawned on me that its wings were dark gray, not pale, silver-gray.
Since I don’t carry field guides on my nature walks (I rely on my camera to capture images while out in nature and identify the subjects at home), the best I could do was make note in my field notebook that the butterfly looked similar to an Eastern Tailed Blue but that I thought it was something new to me.
Later, I consulted my reference field guides and discovered I was right. It was a Gray Hairstreak Butterfly.
My first sighting!
Conditions
|
Temperature |
77° F / 25° C |
|
Weather |
Passing clouds |
|
Humidity |
46% |
|
Time Of Day |
12:30 PM |
|
Setting |
Lakeside greenway, Oak/Hickory forest |
Scientific Classification
|
Kingdom |
Animalia (animals) |
|
Phylum |
Arthropoda (arthropods) |
|
Class |
Insecta (insects) |
|
Order |
Lepidoptera (butterflies and moths) |
|
Family |
Lycaenidae (gossamer-winged butterflies) |
|
Genus |
Strymon |
|
Species |
S. melinus |
Scientific Name |
Strymon melinus |
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