Strymon melinus

Geographic Range

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 nearctic
  • native native
• neotropical neotropical
  • native native

Habitat

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.

• Habitat Regions
• temperate temperate
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• rainforest rainforest
• mountains mountains

• Other Habitat Features
• suburban suburban
• agricultural agricultural

Physical Description

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.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes colored or patterned differently

Development

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 metamorphosis
• diapause diapause

Reproduction

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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

There is no parental involvement once eggs are laid.

• Parental Investment
• pre-fertilization
  • provisioning

Behavior

The adults are quick fliers and are seen most often between the months of May and September. They like to bask in the sun with wings spread wide, unlike most hairstreaks, but they also rub their hindwings together in the typical fashion of most hairstreaks. This back-and-forth movement makes the wings look like anntennae, apparently to fool predators into attacking a less vital part of their body. They are best seen when at rest and their wings are folded together over the back, one hind wing sometimes raised while the other is lowered.

• Key Behaviors
• flies
• diurnal diurnal
• motile motile
• hibernation hibernation

Food Habits

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.

• Primary Diet
• herbivore herbivore
  • folivore folivore
  • frugivore frugivore
  • nectarivore nectarivore

• Plant Foods
• leaves
• fruit
• nectar
• flowers

Ecosystem Roles

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

Economic Importance for Humans: Positive

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.

Economic Importance for Humans: Negative

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

Conservation Status

Gray hairstreaks are not currently endangered or threatened.

Other Comments

This butterfly is so abundant across the United States that some suggest that besides the monarch it should be named the national butterfly.

Additional Links

Encyclopedia of Life

Contributors

Matthew Wund (editor), University of Michigan-Ann Arbor.

Lauren Rodriguez (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

References

Carter, D. 1992. Butterflies and Moths . New York: Dorling Kindersley.

Drees, B., J. Jackman. 1998. A Field Guide to Common Texas Insects . Houston: Gulf Publishing Company.

Milne, L., M. Milne. 1980. The Audubon Society Field Guide to North American Insects and Spiders . New York: Alfred A. Knopf, Inc..

Scott, J. 1986. The Butterflies of North America: A Natural History and Field Guide . California: Stanford University Press.

Tveten, J., G. Tveten. 1996. Butterflies of Houston and Southeast Texas . Austin: University of Texas Press.