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| Gray Hairstreak butterfly (Strymon melinus): perched on Ashyleaf buckwheat. |
July is a great month for
butterflies, with many species at their peak numbers. Gardeners who have chosen
plants to attract butterflies are justly rewarded this month. Due to our continuing Western drought, gardens
are becoming ever more important for beneficial insects (like
butterflies). To learn more about
gardening for butterflies see: http://mother-natures-backyard.blogspot.com/2012/06/butterfly-gardens.html
Among the first butterflies noticed
by many gardeners are the big, showy species like the Monarchs, Gulf
Fritillaries and Swallowtails. But
equally interesting – and important to the garden ecosystem – are the smaller
butterflies. One of our favorites is the
Gray Hairstreak - Strymon melinus.
The
Gray Hairstreak is a common species in most parts of the continental U.S. and
south to Venezuela. It’s the most common Hairstreak seen in many gardens; you may
have noticed it in your own garden, particularly if you grow flowering plants. Strymon
melinus is one of our smaller butterflies, with a wingspan of 7/8 - 1 3/8
inches (2.2 - 3.5 cm). Like the
Swallowtails, the Gray Hairstreak has a single ‘tail’ on the hindwing.
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| Gray Hairstreak butterfly (Strymon melinus): feeding on Ashyleaf buckwheat (Eriogonum cinereum) |
When
perched or feeding, a Hairstreak’s wings are usually closed, making the
underside of the wing more commonly visible.
The underside is mostly gray, with spring and fall flying adults a
darker gray than those of summer. On close
observation, the wings have a thin, pale fringe and thin rather straight black
and white band near the edges of both the fore (front) and dorsal wings. More conspicuous is a darker, more irregular
band of blotches that are white, black and orange (see below). Gray Hairstreaks also have two large orange
and black splotches on the hindwing.
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| Gray Hairstreak butterfly (Strymon melinus): close-up of underside of wings |
The
Gray Hairstreaks we’ve seen have dark eyes and light-and-dark banded antennae
with an orange tip. The heads often have
a patch of orange on the back of the head.
The abdomen of females may have a red or orange tinge. The upper-side is blue-gray with a large
orange-red spot near the ‘tail’. For
more good photographs see refs. 1-5, below.
The
larvae (caterpillars) have the typical form of Hairstreak larvae. They are rather flattened, with distinct
segments and a slightly tapering abdomen.
Color can range from almost gray
through tan, green and even rosy pink or purple. Earlier chrysalids hatch 7-10 days after
pupating (forming a cocoon); fall ones hibernate over winter. Unfortunately, we don’t have any photos of
the larvae or chrysalids. For excellent
photographs – plus advice on raising Strymon
melinus – see reference 6.
Gray
Hairstreaks can be seen much of the year in warm climates. They have two flights (sets of hatchlings)
per year in colder climates and at higher elevations (May to September). They often have 3-4 flights
(February-November) in warm climates like the lower elevations of S.
California. Males can be seen perched on
warm afternoons, waiting for receptive females. Eggs are laid on the flowers of a variety of
host plants – most often in the Pea (Fabaceae)
or Mallow (Malvaceae) families. The young larvae eat mostly flowers and
fruits; later stages may eat leaves as well.
In agricultural areas, this species may become a minor pest on bean and
cotton crops. [5]
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| Gray Hairstreak butterfly (Strymon melinus): on Eriogonum parvifolium |
In
our gardens, we most often see males perched on upright stems or leaves - or individuals
feeding on a wide range of flowers.
Perched individuals often rub their wings together – a behavior commonly
seen in Blues, Coppers and Hairstreak butterflies. The reason for this behavior is unknown; it
may be a defensive mechanism, drawing attention to the abdomen rather than the
head. But whatever the purpose, it’s an
interesting behavior to observe.
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| Gray Hairstreak butterfly (Strymon melinus): nectaring on Ashyleaf buckwheat. Note long, thin proboscis. |
Gray
Hairstreaks inhabit a wide range of sites, in large part due to their
relatively unspecific food requirements.
Adults obtain nectar from many plant species. In our gardens, the most popular seem to be
the native Buckwheats (Eriogonum
species), the Mints (including Salvias), the many-flowered Sunflowers
(Goldenrods, Goldenbushes and Telegraph
plant), Milkweeds and clovers. We’ve
also seen them on Globe Gilia (below) and they are known to frequent other
native and non-native garden flowers.
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| Gray Hairstreak butterfly (Strymon melinus): on Globe gilia (Gilia capitata), Mother nature's Backyard. |
The
larvae are also less selective in their food requirements than many native
butterflies. The host plants are mostly
herbaceous annuals and perennials, commonly in the Pea or Mallow families. Recorded local host species include garden beans
(Phaseolus), native Lotus species, clovers (Trifolium species), Amorpha (false indigo), mallows (including hibiscus), Humulus (hops), Polygonum species, Eriogonum
(Buckwheats), Salvia (Sage) species
and cotton. There likely are other host
plants, yet to be discovered. Grow any
of these to provide an incentive for Gray Hairstreaks to live in your garden.
So
what role do Gray Hairstreaks play in the open woodlands, prairies, parks and
gardens in which they reside? First,
they act as minor pollinators for the flowering plants they visit. They are not the most important – that role
goes to bees and pollinator flies. But they do their part by increasing the
diversity of pollinator species, helping to insure the livelihoods of insect
pollinated plants. In addition, the
larvae of all butterflies and moths are an important source of protein for
birds and even some insects.
Gray
Hairstreaks also contribute to the beauty and interest of local gardens. They are fun to watch and observation can be
done close to home. You may want to
record your observations – and send your photos to iNaturalist (https://www.inaturalist.org/). You may
even discover a new host plant for Strymon
melinus – right in your own backyard!
Like this
posting? See our other insect posts at: http://mother-natures-backyard.blogspot.com/2016/07/insect-postings-mother-natures-backyard.html
_______________
We encourage your comments below.
If you have questions about garden butterflies or other gardening
topics you can e-mail us at : mothernaturesbackyard10@gmail.com
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