A Stowaway from Eagles Rest

Last year, I discovered the caterpillars of dotted blues on barestem buckwheat (Eriogonum nudum) in the lower opening at Eagles Rest (see Butterfly Discovery at Eagles Rest). I had hoped that I would be able to find more there this year, now that I knew when and where to look. But the severe shortage of rain this past spring caused the normally seepy lower tier where the buckwheat grows to dry out much sooner than usual. A trip in early June was rather depressing—a number of plant species seemed to be drying up without ever having bloomed. I saw no dotted blues, adults or caterpillars.

A golden hairstreak up in the chinquapin.

It wasn’t until August 6th that I returned to Eagles Rest to collect whatever seeds I could find while enjoying the short afternoon hike and pleasant view. I managed to collect seeds of paintbrush (Castilleja hispida and pruinosa here, I believe), barestem buckwheat, Rattan’s penstemon (Penstemon rattanii), and a few bulbs.

One of the few things that was in bloom in August at this fairly low elevation (only 3000′ at the summit) was golden chinquapin (Chrysolepis chrysophylla—”chryso” means golden, so this species is really golden). This is the sole host food plant for golden hairstreaks (Habrodais grunus) in this area, and their flight period is late, usually coinciding with the flowering of the chinquapin. Hoping to see some, I hung out on the summit by the cluster of chinquapins along the top for a short while before I was rewarded with a glimpse of gold fluttering about high in the trees. Sure enough, it was a golden hairstreak!

This golden hairstreak came quite a bit closer, although this was still taken with a zoom lens. While it doesn’t have a prominent pattern on the end of its wing, it does have the telltale tail of a hairstreak.

Several more appeared chasing each other through the little forest of chinquapins. One would land on a leaf occasionally, but before I’d have a chance to get a photo or even get much of a look, another would come by, chase it off, and the game would begin again. I’m not sure if they were playing a game with each other, but it sure seemed like they were playing with me—they seemed to know precisely when I was about to click the shutter before zipping off and disappearing for five minutes or so. Most likely, they were going through a mating ritual and barely noticed me. As a late summer butterfly, golden hairstreaks overwinter as eggs, finishing the rest of their life cycle the following year, so they had to get going so they could start laying eggs. Life Histories of Cascadia Butterflies says it has been reported that they may rest in the shade most of the day and become active after 3 pm. It was around 5 pm, so apparently I hit it right. 

The gray hairstreaks enjoyed the chinquapin flowers.

None of the golden hairstreaks ever seemed to land on the flowers, but there was another visitor that was more interested in nectaring on the copious flowers. At least a couple of gray hairstreaks (Strymon melinus) were relaxingly visiting the flowers and ignoring me and the other butterflies. They nectared for quite some time but always high up in the trees where I couldn’t get a very close look.

You can see the steel-blue upperside of this gray hairstreak nectaring on chinquapin. The bright coloration near the tail is supposed to lure any predators to attack the relatively unimportant end of the wing rather than the true head of the butterfly. Perhaps the golden hairstreak doesn’t have this because it is so well camouflaged in the chinquapins.

I kept trying to photograph both butterfly species and would occasionally get a decent, though distant shot. But every time I thought, “That’s it, I give up,” another one would land tantalizingly close. Eventually, several golden hairstreaks alighted briefly in the lower branches long enough for me to get a quick shot. After over 45 minutes, I finally tired of this hide and go seek, and satisfied I’d gotten at least a few decent shots, I decided to head home.

The chinquapin inflorescences are golden as are the undersides of the leaves. Did you notice the caterpillar right away? I didn’t!

Before leaving, I thought I’d grab a small branch of the chinquapin to bring home and look more carefully at the drab little flowers with their profusion of long stamens under the microscope, so I grabbed one of the lower branches and stuffed it into a bag in my pack. When I arrived home, I took it out to show my husband and see what he thought of the distinct, not particularly pleasant odor of the flowers. He instantly noticed something I hadn’t—a “stowaway.” Sitting on one of the leaves was a small, slug-like caterpillar! How had I not noticed that? Guess I was so focused on adults, I hadn’t thought to look for caterpillars after not finding any dotted blues on the buckwheats. My first assumption was that it was the caterpillar of a golden hairstreak—something I’ve long wanted to see but never found. But after checking out my go-to caterpillar book, Life Histories of Cascadia Butterflies, I decided it had too much pink and was probably actually the larva of a gray hairstreak. It was also probably too late in the year for caterpillars of golden hairstreaks. Unlike the golden hairstreak, gray hairstreaks have a very varied diet. The ones I’d found last year (see A Sea of Blue at Maple Creek Meadow) were eating in the inflorescences of rose checkermallows (Sidalcea asprella [formerly malviflora or virgata]), but they are reported to eat a wide range of species from many different families and often favor flowers. David James, one of the authors of this fantastic book, kindly confirmed my ID. 

The little pinkish caterpillar sitting on the chinquapin branch I brought home.

Now I had to take care of my little friend, so I set it up in a little vase where it promptly started nibbling on the chinquapin flowers. After a week or so, it disappeared. At first, I was concerned it had gotten out of the container, but then I found it under the paper towel below the vase, and it had changed into a chrysalis. Unfortunately, I missed the major transformation. Hopefully, it will survive the winter, and next spring it will join the gray hairstreaks that already live on my property.

The caterpillar was noticeably pinker several days after I inadvertently brought it home.

The gray hairstreak chrysalis on October 11, hunkered down for a long winter’s nap. Fingers crossed it wakes up as a butterfly next spring!

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