Creature Feature: Spicebush Swallowtail
A stand of Spicebush along the creek results in an abundance of Spicebush Swallowtails Papilio troilus flying low and fluttering their wings while they feast on summer's abundant flowers.
A stand of Spicebush along the creek results in an abundance of Spicebush Swallowtails Papilio troilus flying low and fluttering their wings while they feast on summer's abundant flowers.
Walking through the woods in late summer, you might be rewarded if you examine Spicebush leaves, especially leaves that are rolled over. Lurking inside this leaf-retreat, is what appears to be a snake or maybe a tree frog (exactly what the caterpillar wants predators to think!) They might even rear up and retract their head to increase the illusion.
A true mimic, early stages of the caterpillar resemble bird poop, and the adults resemble the poisonous Pipevine Swallowtail Battus philenor.
Spicebush Swallowtail caterpillar Photo courtesy of Ellen Reynolds, Beagle Ridge Herb Farm
Photo by Bill Dunson
Do you remember the butterfly life cycle?
Butterflies feed on nectar from a variety of flowers, then the females lay eggs on a suitable host plant. While some butterflies lay eggs on a variety of plants, more often they limit themselves to a specific plant, such as Monarchs Danaus plexippus and Milkweed Asclepias spp., or a plant family such as Spicebush Swallowtails Papilio troilus and the family Lauraceaea which includes Spicebush Lindera bezoin and Sassafras Sassafras albidum.
In addition to sight, females utilize chemical receptors on their forelegs to assess the chemicals in the leaf to decide if it is an suitable host. Once the eggs hatch, caterpillars eat the leaves of the host until they are large enough to pupate. Then they will spin a chrysalis and complete their transformation into a butterfly.
Never ending discovery
Spicebush Swallowtail Caterpillar (pre-pupal coloration)
©Scott Jackson-Ricketts
After the Radford BRDC Board Meeting, Devin and I regrouped at my place in Grayson County. After some review of the day’s events, we took a short but productive walk between my house and shop, mostly along the driveway. A few days prior, while being the busy guy in my shop, I found a caterpillar climbing up one of my recently painted shelving boards, which turned out to be a late instar spice bush larva. The information we sought while trying to understand the unique color of this caterpillar confirmed that just before it pupates, its color changes from green to orange, yellow or some combination therein. I would call what these pictures convey, peach.
Going on that inspiration, we headed straight to the spice bush known to me near my shop. Devin and I spent some time trying to find either another caterpillar or a pupated form, which Devin might have discovered five feet from the bush on the downside of a leaning black cherry tree. His photos reveal that what he found is indeed a swallow-tail, but not definitively spice bush. Another contender could be eastern tiger swallow-tail.
After that relative success, and while heading back to the house, we took our time observing activity among the wingstems and other late summer wildflower blooms, just paying that kind of attention we both share. Near the fork in our driveway that becomes the circle serving two homes, we found an unfamiliar wood shrub with both catkins and fruit present on the branches. Neither of us had ever seen this small tree before, and immediately grabbed a fruit sample, both acquiring simultaneously the precious sharp stabs from the needle like covering, reminding us of cacti.
Back at the house Devin immediately went for the field guides and soon reported that the woody shrub was a
. While I cooked up some mush, he spent some time looking through my dissecting microscope, which showed us that the needles were almost glass like in appearance, with the light showing through. Very delicate and sharp, as we already knew, but brought up close, incredibly beautiful.
Beaked hazelnut (Corylus cornuta) fruit detail.©Devin Floyd
Given that our little walk was well under an hour’s time spent, and that I take this walk almost every day, what we discovered in detail was new to me, and serves to remind us all that the quest for discovery is never over.
-Scott Jackson-Ricketts
Photographs © Devin Floyd and Scott Jackson-Ricketts
Rocky Knob Migration Watch, Fall 2010: Report # 1
American Copper (
Lycaena phlaeas
), nectaring on white clover bloom.
Sunday 29 August 2010
Bruce Grimes & I arrived at Rocky Knob at Noon and stayed till 4 p.m. We were playing hooky from a lot of tasks that we both need to get done, but the hours of migration watch were worth it.
First, some background:
Rocky Knob Hawk Watch occurs at milepost 168 on the Blue Ridge Parkway. We watch from the Saddle Overlook sometimes, which gives us a fairly good view of Rock Castle Gorge to the east, and Buffalo Mountain westward. Mostly we watch from a large pasture just to the north of the Saddle Overlook parking lot. We affectionately call this location the Cow Pie Palace.
The hawk watch is occasional, mostly on weekends, and even then we seem to steal time from other activities. I wish that it could be closer to more daily monitoring of migration.
There are other hawk migration watch sites on the Parkway, and these are monitored far more frequently than our migration watch site at Rocky Knob:
Rockfish Gap (aka Afton Mountain)
Harvey's Knob
Mahogany Rock
If you are in this part of the universe, stop by and take a look for yourself: hawks are circling, gliding, soaring, flapping, hurrying or easing southward. So are many other species of birds: ruby-throated hummingbirds, chimney swifts, swallows, thrushes, warblers, tanagers, orioles, and many other kinds. And other creatures are pushing south also: several kinds of dragonflies, mostly common green darners, black saddlebags, wandering gliders, and twelve-spotted skimmers; and several species of butterflies too: besides monarchs, these include, Cloudless Sulphurs, Sleepy Orange Sulphurs, Little Yellows, Variegated Fritillaries, Eastern Commas, Mourning Cloaks, Painted Ladies, American Ladies, Red Admirals, and Common Buckeyes.
As soon as we got there yesterday, we noticed that Common Buckeyes, and Common Green Darners were flying by. We stayed busy trying to watch high and low for species that were on the move. The buckeyes mostly flew low just above grass blade and cow pie, but a few of them were actually fairly high up--one even buzzed a black saddlebags dragonfly, then flew on south. Some of the monarchs and buckeyes, the two most common insect migrants yesterday, would stop a while and refuel at thistle blossoms.
Tally for the 29th:
Raptors:
Osprey 1
American Kestrel 1
Other migrating birds:
Chimney Swift 16
Ruby-throated Hummingbird 5 (two were adult males)
Barn Swallow 5
Scarlet Tanager 2
Migrating butterflies:
Variegated Fritillary 1
American Lady 1
Painted Lady 1
unidentified
Vanessa
sp. 2
Common Buckeye 34
Monarch 31
Migrating Dragonflies:
Common Green Darner 20
Spot-winged Glider 2
Wandering Glider 1
Black Saddlebags 23
Carolina Saddlebags 1
Great Spangled Fritillary (Speyeria cybele), nectaring on thistle.
There were many other species of butterflies nectaring on thistles and other flowers in the fields: seemed to be gazillions of Pipevine and Eastern Tiger Swallowtails, one female Black Swallowtail, a few Spicebush Swallowtails, lots of Great Spangled Fritillaries (probably close to 100) and three Aphrodite Fritillaries, and one male Diana Fritillary. There were a few American Coppers, and a small horde of Peck's Skippers and Sachems!
The one Painted Lady that migrated through the field, stopped a couple of times for a portrait pose while it nectared on some flowers. Bruce got some pictures of this critter, plus some of the other butterfly species.
Hopefully there will be a few more migration reports during September. Please do stop by and check out the migration scene at Rocky Knob.
Painted Lady (Vanessa cardui), nectaring on a thistle flower. Thistles are also host plants for the caterpillars. Painted Ladies have nearly worldwide distribution, and are one of the most common migrating butterflies in the world.
Those confusing black and blue butterflies!
Well it is Spring again, that most wonderful time of year when life renews itself, and we have to figure out the names of all those confusing Spring flowers and butterflies that we have not generally seen for many months. I just encountered my first spicebush swallowtail butterfly and since it was a male, it was relatively easy to recognize (see photo). However there are a surprising number of large black and blue butterflies, many in different families and thus not closely related, that resemble one another to an amazing degree. Just for example consider the photos of four species that I have included here: the spicebush and pipevine swallowtails, the female Diana fritillary, and the red-spotted purple (a brushfoot). Considering that the males and females of some species are much more different in appearance than these butterflies from totally different families, what is going on here?
This is believed to be the result of convergence in coloration among butterflies that are poisonous to eat (especially the pipevine swallowtail that feeds on toxic Dutchman's pipe as a caterpillar and thus serves as a model) and tasty or partially tasty mimics that find it advantageous to gain protection from a resemblance to the pipevine swallowtail. Yet why would males and females within one species be so different? For example male eastern tiger swallowtails are yellow and black as are many females, yet some females are dark, especially in the South. Male and female Diana fritillaries are always different and the male is more cryptic.
This similarity in coloration among dissimilar species should remind you of the mimicry group among orange and black butterflies (all poisonous to some degree) that feed on milkweed (monarch, queen, soldier), willow (viceroy) and passionvine (gulf fritillary).
So the predators, mainly birds, are clearly scrutinizing their prey in great detail trying to figure out which ones are good to eat and which are poisonous. The prey are doing their best to confuse the birds. The military "arms race" and strategic deterrence were obviously not invented by the Russians and Americans. Once again we are amazed by the diversity and complexity of life!
-Bill Dunson
Galax, VA & Englewood, FL