Gray Hairstreak
The Gray hairstreak (Strymon melinus) is one of the most common lycaenids in North America. Its larvae feed on the fruits and flowers of a variety of host plants including several species mallows, members of the pea family, buckwheats, clovers, and many other plants.
Sometimes, larvae are not too difficult to find in the flowers of these host plants when they are tended by ants. In other words, look for congregations of ants when looking for caterpillars. (This video teaches this general principle.)
The following slide show demonstrates techniques for finding and caring for gray hairstreaks in Northern Utah that feed on buckwheat. It can be applied to other parts of the Western U.S. where Eriogonum racemosum and possibly other species of buckwheat support this butterfly in the late summer and fall.
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Gray Hairstrak Male Butterfly
Both the dorsal and ventral surface of the gray hairstreak are shown here.
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Redroot Buckwheat in bloom
The flowers of redroot buckwheat (Eriogonum racemosum) is one of the many species of plants that the gray hairstreak larvae will feed on. Although this plant has green basal leaves that are visible in the spring, this plant doesn't usually bloom until late summer. When it does, througout much of its distribution, the gray hairstreak will utilize this plant. (At the same time, in many places in the Rocky Mountains, gray hairstreaks will also use Astragalus spp. that are in bloom during the spring months.)
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Redroot Buckwheat in bloom
Close up photo of the blooms of redroot buckwheat. Sometimes the flowers are pink; sometimes they are white.
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Gray Hairstreak Fourth Instar Larva Tended by Ant
Because gray hairstreak caterpillars camouflage themselves so well on the redroot buckwheat flowers, it is always helpful to also look for ants that are tending these gray hairstreak caterpillars.
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Feeding Gray Hairstreak Caterpillars
Because gray hairstreak caterpillars can be cannibalistic, it becomes practical to rear them in separate containers such as storage containers, squat tubs, or restaurant supply condiment containers (i.e, solo cups.) Using closed containers is advantageous over using terrariums or buckets in that it lowers the setup time; but also is more time consuming because you generally need to change out caterpillar frass and host plant every day. Make sure you puncture holes in these closed container to allow caterpillar frass to dry.
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Closed Container Method II
The lids of these containers have holes poked around them; so that caterpillar poop can dry and the larvae don't get sick.
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Twin Cup Method
Another alternative to rearing gray hairstreaks in closed containers is to use the twin cup method. The advantage of this method is that the stalks of the host are in water and it stays fresher longer where you don't have to change it out once or twice a day. To set it up, simply place host cuttings through the hole of one cup to rest in another cup of water. Last, place a screen lid on top. This video demonstrates how this is accomplished. -
Gray Hairstreak Fourth Instar Caterpillar
This gray hairstreak caterpillar is feeding on the blossoms of redroot buckwheat.
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Gray Hairstreak Fourth Instar Caterpillar
Gray hairstreak caterpillars show caterpillar color variation consistent with the same variability of the blossoms of redroot buckwheat--ranging from pink to white.
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Spalding Blue Caterpillar
Another butterfly caterpillar that feeds on redroot buckwheat that you might find is the spalding blue (Euphilotes spaldingi). The main difference between these two larvae is evident on the pattern of the lines on the mid-dorsum (back). On the spalding blue, there is a single reddish line; whereas the pattern on the gray hairstreak is more a double line or a series of quotation marks.
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Gray Hairstreak Prepupa
I don't have a photo of a gray hairstreak larva that is ready to form a chrysalis; but lycaenid larvae tend to change color when they are finished eating and are ready seek a place to pupate and form a chrysalis.
Examples of this can be seen in this section of the website. One practical option is to place them in facial tissue and fold into three equal rectangular sections. Then, rotate 90 degrees and fold into thirds again. (If that sounds complicated, watch the first minute of this video.)
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Easy Place for Gray Hairstreak Larva to Pupate
Once you've placed your mature larva on facial tissue, and folded into a "pillow", place that into a squat tub for 3 days while waiting for your larva to pupate.
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Gray Hairstreak Pupa
Here is a photo of the gray hairstreak pupa. It usually takes about 7-10 days for your pupa to emerge into a live butterfly UNLESS, of course, the pupa has entered diapause; in which case you would need to overwinter your pupa before it emerges. Instructions on how to overwinter your pupa can be found here. Photo courtesy Nicky Davis.
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Gray Hairstreak Emerges into an Adult Butterfly
Photos courtesy Nicky Davis.
