Welcome to my happy place. The image above features a cloudless sulpher (Phoebis sennae) caterpillar on its host plant, native wild senna (Senna hebecarpa). I took the picture at the Botanical Gardens of Asheville about a month ago. Jay, the garden manager, and I have declared 2017 the year of the caterpillar. We’ve seen a record number of caterpillar species this year and have relied heavily on one field guide in particular for ID. Today, I’ll tell you about that book along with two other must-haves for butterfly lovers:
1) “A Pictorial Guide to the Monarch Butterfly Migration over the Southernmost Blue Ridge Parkway, Fall 2017” by Asheville’s own Mickey Hunt, $9.34;
2) “Monarchs and Milkweed; A Migrating Butterfly, a Poisonous Plant, and Their Remarkable Story of Coevolution” by Anurag Agrawal, $29.95; and
3) “Caterpillars of Eastern North America,” a Princeton Field Guide by David Wagner, $29.95.
Mickey Hunt (chaoticterrainpress.blogspot.com) regularly comments on my blog, but I hadn’t met him in person until this week when he dropped off a copy of his new book “A Pictorial Guide to the Monarch Butterfly Migration over the Southernmost Blue Ridge Parkway.”
I can’t tell you how long I’ve pined for a field guide like this. (We now carry them at the Botanical Gardens at Asheville’s Visitor Center, so come pick one up during our business hours. You can’t beat the price at $9.34.)
Why do you need this book? Beginning in mid-September, the last generation of monarch butterflies born in North America start migrating through Western North Carolina. We get to enjoy this sight through October, and certain overlooks on the Blue Ridge Parkway provide the best place to see multiple monarchs on the wing. Mickey gives a nice overview of the monarch lifecycle and migration and lists the specific locations and mileposts where monarch lovers will most likely to see these lovely creatures making their migration. Like the broad-wing hawks, which migrate through in mid-September, the monarchs catch thermals (upward air currents) through our mountain valleys. These thermals allow the butterflies to coast, so they spend less of their precious stores of energy flapping their wings.
Last fall, I took my niece, Hadley, to Pounding Mill Overlook (mile 413.2) where we saw quite a few of these migrants, including the one pictured below.
In his book Mickey writes, “Your best chances to see them on the parkway are on sunny days, in the middle of the day, with light breeze from the north. In those conditions in the right locations you can find dozens flitting about feeding on goldenrod and aster blooms.”
So, if you live in Western North Carolina, get the book and then get thee to the Parkway!
This September, I gave a class at the Botan called “Monarchs and Milkweed,” based on the research presented by Anurag Agrawal in his book “Monarchs and Milkweed; A Migrating Butterfly, a Poisonous Plant, and Their Remarkable Story of Coevolution.”
Agrawal, a professor in the entomology and ecology and evolutionary biology departments at Cornell University, takes readers on a deep-dive into the chemistry of milkweed and details the ability of the monarch butterfly to sequester the plant’s toxins as a defense against predation. I learned so much from this superb book.
For one thing, Agrawal disabused me of the notion of the monarch as a friendly pollinator of milkweed. As you know, a monarch female lays her eggs on milkweed, the only plant her caterpillars will eat. The monarch, along with 10 other insect pests, is an enemy of the milkweed. The adult monarch doesn’t even do the service of spreading pollen as it nectars on milkweed flowers. That’s because, unlike 90% of plants that have loose pollen grains, the milkweed keeps its pollen in a wishbone-shaped package called a pollinia (or pollen sac). Bees do the heavy lifting of extracting the pollinia sacs from one flower and inserting it into another flower’s female part. (Cool post on the Eye on Nature blog with more details on milkweed pollinia, here.) Agrawal explains that monarchs, “with their long legs, simply don’t contact the business-end of the milkweed flower.” Agrawal says that butterflies in general aren’t the greatest pollinators.
I wanted to find a picture of the pollen sacs among my own milkweed photos. After reading about them in Agrawal’s book, I scrolled through the pictures I’ve taken of bugs on my milkweed. Entomologists call the cutie below the banded tussock moth (Halysidota tessellates), and I find it regularly in my milkweed patch during the milkweed bloom season:
Next, I looked at a picture of this moth on a milkweed leaf and … what on earth!? Could it be?! I zoomed in on the picture and, to my great delight, saw pollinia sacs stuck on the moth’s tootsies like cute little flip-flops.
Gang, this made my day.
And, yes, I know I’m a nerd and possibly a dork, but you are too if you’re still reading this far.*
[*With the exception of the ladies of my writing group, who (whom?) I’ve forced to read this — but you might be dorks for associating with me. I know! This is full of passive verbs! But it’s 12:28 am, so I’m being lazy. Gah, I can’t stop with the passives. And, sorry, Deb. The description of the pollinia is the closest thing I’ve got to a sex scene.]
Anyway, the monarch “pest” doesn’t help the milkweed, so the plant has come up with some clever defenses — namely leaf hairs (trichomes) to foil the newly hatched caterpillars and pressurized poison in the plant’s latex. And the monarch caterpillar has developed clever ways around these defenses. For example, a newly hatched monarch will bite into the leaf and retract its head to avoid a shower of sticky poisonous sap. Agrawal said that in one study of 3,000 monarch eggs on nine different milkweed species “more than 60% of monarchs died in the burst of latex that accompanied their first bites into the plant.” Those that survive continue biting until they’ve created a trench. With the latex stopped by the trench, they can feed on the leaf in peace.
I learned so much from this book and will revisit it in future posts, but I need to move on for now. Let me just say that in this newly-turned-upside-down world, science gives me such comfort. I so look forward to the day when a fact’s a fact and reason and civility and common decency come back around.
I have one more book that I want to recommend in this post:
“Caterpillars of Eastern North America,” a Princeton Field Guide by David Wagner, a 512-page, full-color reference and ID guide to caterpillars. We use it quite a bit at the Botan, and it’s the best caterpillar guide I’ve found to date.
I do wish it featured every instar (stage) of each caterpillar. If you know of a guide that includes the instars, please let me know in the comments below.
Cheers until next time — and maybe I’ll see you on the Parkway this week!