Strymon melinus

Strymon melinus is a resident throughout the United States and into southern Canada and ranging south to Venezuela (Scott 1986). Habitats are tropical to transition zone open areas. Host plants are herbs, trees and shrubs from multiple families, including Leguminosae. Eggs are laid on host inflorescences singly. Individuals overwinter as pupae. There are multiple flights each year from spring to fall (Scott 1986).

The Grey Hairstreak has an ash-grey undersurface with a prominent white-bordered, black median line, and two orange patches in the outer angle of the hindwing. Grey hairstreaks have a patch of orange hair between the top of the eyes, which is unique among Alberta hairstreaks. The subspecies affiliation of Alberta populations remains uncertain (Bird et al. 1995), although they have sometimes been reffered to ssp. franki (Layberry et al. 1998, Guppy & Shepard 2001).

This is one of the most widespread of the hairstreaks, occurring from southern Canada south through the entire US to Central and South America (Opler 1999).

Gray hairstreaks can be found in Southern Canada to Central America and Northwestern South America. They occur from coast to coast and in a variety of altitudes ranging from sea level to nine thousand feet.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) North America as far north as British Columbia and the Canadian Maritime Provinces. Also south to Venezuela and Columbia.

In the earlier stages of the life cycle, gray hairstreaks are straw, purplish-white, pink, reddish-brown, or green larvae with various other paler marks. The head is yellowish-brown. Throuhout Texas, however, the larvae have been noted to be entirely green and covered with short hairs. The pupae hibernate and are usually brownish in color. In the adult stages of the life cycle the butterfly's upper wings are dark grayish brown with a prominent orange spot located at the outer margin close to the shorter of the two blackish tails. The conspicuous orange spot is larger than most Strymon species. The hind wing is gray (darker in males and spring adults than in females and summer adults). It too has a black-eyed orange spot at the bases of the hindwing tails. There is a small patch of blue before the tail, and two broken crossbands of black and white spots. The male abdomen is orange. The wingspan varies from 2.6 to 3.65 cm.

Range wingspan: 2.6 to 3.65 cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: sexes colored or patterned differently

In Alberta, primarily a grassland species found in badlands and along coulees and ridge tops.

Unlike most butterflies, gray hairstreaks do not prefer one specific habitat. They are widespread in tropical forests and open, temperate woodland areas. They can also be found in meadows, crop fields, neglected roadsides, and residential parks and yards are often homes of this fascinating butterfly.

Range elevation: 0 to 2745 m.

Habitat Regions: temperate ; tropical ; terrestrial

Terrestrial Biomes: forest ; rainforest ; mountains

Other Habitat Features: suburban ; agricultural

Comments: A vast array of open to lightly wooded habitats where foodplants such as various mallows, legumes and HYPERICUM grow. Seen in forest mainly in the spring before canopy closure. Mobile and can turn up in any open habitat.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Larvae feed on a huge variety of plants and have been recorded from over 20 plant families (Layberry et al. 1998). Despite this, larvae appear to be specialized feeders in that they consume primarily flowers and developing seeds (Guppy & Shepard 2001). A number of legume hosts have been recorded in BC, including native clovers (Trifolium spp.) and cultivated green beans (Guppy & Shepard 2001). Larvae are occasionally crop pests on beans, cotton and hops in the US (Layberry et al. 1998).

Just as in many other characteristics of gray hairstreaks, their food habits are general. Neither the caterpillar nor the butterfly are specific to any certain plant or flower, but rather feed on a variety of plants. The larvae eat from at least twenty different families of plants, including the pea and mallow families. Normally they can be found eating fruits and flowers. They can also be found on maize, cotton and a variety of shrubs and trees. The butterfly feeds on nectar from a wide variety of flowers.

Plant Foods: leaves; fruit; nectar; flowers

Primary Diet: herbivore (Folivore , Frugivore , Nectarivore )

Strymon melinus Hübner: Lycaenidae, Lepidoptera
(observations are from Robertson, Hilty, Clinebell, Fothergill & Vaughn; this butterfly is the Gray Hairstreak)

Apiaceae: Eryngium yuccifolium sn (Rb); Asclepiadaceae: Asclepias incarnata [plab sn] (Rb), Asclepias sullivanti [plab sn] (Rb); Asteraceae: Aster pilosus sn (Rb, H, FV), Boltonia asterioides sn (Rb), Coreopsis palmata sn (Rb), Echinacea pallida sn (Cl), Erigeron philadelphicus sn (FV), Heliopsis helianthoides sn (Rb), Pluchea camphorata sn (FV), Ratibida pinnata sn (Rb), Rudbeckia subtomentosa sn (Rb), Solidago gigantea sn (FV), Taraxacum officinale sn (FV), Vernonia fasciculata sn (Rb); Caprifoliaceae: Viburnum prunifolium sn (Rb); Fabaceae: Lespedeza virginica sn np (Rb), Melilotus alba sn (Rb), Trifolium repens sn (FV); Lamiaceae: Pycnanthemum tenuifolium sn (Rb); Polygonaceae: Persicaria hydropiperoides sn (FV); Rubiaceae: Cephalanthus occidentalis sn (Rb); Santalaceae: Comandra umbellata sn (Rb); Verbenaceae: Phyla lanceolata sn (FV), Verbena stricta sn (Rb), Verbena urticifolia sn (Rb)

These generalists feed on (and likely pollinate) a wide variety of plants. They also may be eaten by a wide variety of predators.

Ecosystem Impact: pollinates

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

10,000 to >1,000,000 individuals

Likely two broods annually, peaking in mid May and mid July.

The larval colour pattern is variable, ranging from green with white to purple oblique bands (Layberry et al. 1998). Adults are rapid flyers, and perch head-down on vegetation (Bird et al. 1995). Unlike other hairstreaks, melinus overwinters as a pupa and emerges in the spring (Guppy & Shepard 2001).

After about six days the eggs hatch, and over the next twenty days the caterpillars grow and develop. They then form a chrysalis and after about ten days emerge as adults. Silvery-blues spend the winter as pupae and can have three or more generations per year. Development time can vary greatly depending on geography and the different hosts.

Development - Life Cycle: metamorphosis ; diapause

Mating and egg-laying occur in early spring. Adult males perch on small trees and shrubs from early afternoon to dusk to await females. They usually perch at a level where they can catch cooler breezes, lower to the ground in the spring and higher as the year goes on. Males back dorsally. Mating pairs are normally spotted at night, and females oviposit during the midafternoon. The females then lay their pale green eggs on hosts' buds or newly opened flowers of the host plant.

Breeding season: early spring

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous

There is no parental involvement once eggs are laid.

Parental Investment: pre-fertilization (Provisioning)

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 6 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 6
Specimens with Barcodes: 66
Species With Barcodes: 1

Rare and local in Alberta, primarily restricted to grasslands.

Gray hairstreaks are not currently endangered or threatened.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Reasons: Widespread species; occasional economic pest of beans, hops, and cotton.

Other Considerations: May be excluding Strymon avalona from Catalina Island, the only area where it occurs.

Degree of Threat: D : Unthreatened throughout its range, communities may be threatened in minor portions of the range or degree of variation falls within natural variation

Global Protection: Many to very many (13 to >40) occurrences appropriately protected and managed

The larvae of gray hairstreaks, when abundant, can become pests to commercial crops, including cotton, beans, corn, and hops. Habits such as these have earned the caterpillar the common name of "cotton square borer" and "bean lycaenid".

Negative Impacts: crop pest

Gray hairstreaks benefit humans just as so many other butterflies, bees, and small birds do. The butterfly participates in a mutualistic relationship with many flowering plants by receiving nutrients (nectar) and acting as a pollinator.