Big Butterflies #3: Zebra Swallowtail

While shooting eastern tiger swallowtails in the joe-pye weeds, out of the corner of my eye I kept seeing something large and white darting about in the New York ironweed. I only managed to get a few blurry pictures of it before it disappeared altogether. There’s no doubt what it was: a zebra swallowtail (Protographium marcellus, formerly Eurytides marcellus).

The next day I was outside tending to something else when I saw it again. This time I dashed inside, got the camera, and dashed back outside to the low fence that separates my property from the road. Along this fence I’ve planted understory trees and shrubs, and a few perennials. Among these are two small pawpaws, and that’s where the zebra swallowtail was.

For half an hour I observed its behavior. It would flutter about the pawpaws, settling for maybe a second or two at a time, then it would head south and check out the joe-pyes and ironweeds, then it would make a big loop up the street and come back over the fence on the north side of the yard, gliding back through the trees and shrubs to flutter about the pawpaws again. Sometimes it made a big loop through my yard instead; always it returned to the pawpaws.

The males are known to patrol around pawpaws, looking for females. Pawpaws (Asimina triloba) are the host plant for the caterpillars. Adult zebra swallowtails feed on nectar from a variety of plants, including dogbane, common milkweed, verbena, redbud, and blueberry. I need to plant some of those by next spring, because I sure would like to see more of these striking insects flying about my yard.

Zebra swallowtails are found primarily in the South, southern mid-Atlantic, and southern mid-West. In Maryland, which is almost as far north as they go, they fly in April and August; further south they fly from March to December.

Apparently it’s difficult to distinguish the females from the males, at least when they’re on the wing, other than by observing behavior. The one pictured in this post might be a male; all the time I observed it, I never saw it laying eggs (the females lay one egg at a time, on the undersides of pawpaw leaves). I also haven’t seen any eggs or caterpillars on the plants, though I’ve been checking every day.

Zebra swallowtails from summer broods have much longer tails than those from spring broods. Click on these pictures to get a better look at just how long those tails are.

 

 

 

 

 

 

ps: here’s a picture of a pawpaw flower; around here, they bloom from about mid April to mid May

Astery Things #3: New York Ironweed

Growing along the fence with the joe-pye weeds in my garden is another oddball asteraceous species: Vernonia noveboracensis, or New York iron weed.

Like the joe-pye species, the inflorescence of NY ironweed consists only of disk florets; there are no rays at all. And what a great example of this kind of flower it is: look closely and you can see how five narrow petals, fused at the base, form a corolla, from which a split style pops way out.

There are two native species in MD; the other one, broad-leaved ironweed (V. glauca), is found in a few locations in the eastern Piedmont and in the Coastal Plain, while New York ironweed is found throughout the state. There’s also an alien, Arkansas ironweed (V. arkansana) reported in one location in the Coastal Plain.

New York ironweed’s native range is from southern New England into northern Florida and west into central Kentucky and Tennessee (and in one county way out in northern New Mexico). It’s listed “special concern” in Kentucky and “presumed extirpated” in Ohio.

Often described as “coarse” in texture, this is a tall forb – over six feet in ideal conditions – with an open habit. It likes moist to wet soils; in the wild you’ll find it growing along river banks, in the full sun or dappled shade.

In the garden site it where it will get enough sun and water, in the back since it gets so tall, or along a fence. It doesn’t attract butterflies as well as the joe-pye weeds do, but bees go crazy for it. And it blooms for a long time.

I was trying to get good, clear close-up shots of the flowers, with the camera mounted on a tripod, but something large and white kept moving around in the upper reaches of the plants. As soon as I realized what it was I took the camera in hand and tried to get pictures of yet another type of butterfly. It never stayed still, so all the shots were lousy and I was pretty bummed… until the next day. More about that in my next post.

Big Butterflies #2: Dark Wings

eastern tiger swallowtail, dark morph: dorsal view, closeup showing markings on hindwings

While researching butterflies I learned that there are six dark-winged swallowtail species in Maryland: the black, giant, palamedes, pipevine, spicebush, and dark morph eastern tiger.

eastern tiger swallowtail, dark morph: ventral view showing hindwing markings

The dark winged butterfly that I had been shooting on joe-pye weeds [see previous post] was a dark morph eastern tiger swallowtail (Papilio glaucus). The dark morphs are always females.

eastern tiger swallowtail, dark morph: ventral view showing body

 

Several characteristics distinguish dark morphs from other butterflies with dark wings, but the one that’s a dead giveaway is the lack of white spots on the body.

eastern tiger swallowtail, dark morph: ventral view showing white “dashes” on wings

 

 

 

 

Also note that the white marks on the trailing edge of the forewing are elongated: dashes rather than spots.

dorsal view

 

 

 

 

 

 

 

 

 

It wasn’t until the next day, while I was shooting yet another species of butterfly (subject of a future post), that I saw what I thought was a spicebush swallowtail (Papilio troilus). I didn’t even realize at the time that’s what it was, because I was so focused on the other one that I didn’t stop to think that this particular butterfly was actually resting on a spicebush.

ventral view

 

Note the round spots on the body, and also the fingertip-shaped bluish markings at the trailing edge of the hindwing. The lack of a lighter patch in front of those blue marks indicates that this is a female. SEE UPDATE BELOW.

Spicebush swallowtails range from eastern Texas north into the Midwest and southern New England, and south into Florida. Several species of plants host the caterpillars, most notably spicebush (Lindera benzoin). Adults feed on quite a few different plant species, including some exotics; among the native species are milkweeds, dogbanes, and thistles.

another dorsal view

I’m totally kicking myself for not hopping the fence that was in my way to get better pictures. I’ve checked my spicebushes several times each day since then, but haven’t seen another butterfly on them.

 

 

giant swallowtail

 

Here’s a giant swallowtail (Papilio cresphontes) that I photographed in the eastern panhandle of West Virginia a few years ago. I’ve never seen one of these around my house; they are found in most of Maryland, but are fairly rare.

 

pipevine swallowtail

I believe this last one to be a pipevine swallowtail (Battus philenor). The plants it’s on are Aristolochia fimbriata, white-veined Dutchman’s pipe, a South American species that’s growing in the Enid A. Haupt Garden next to the Freer Gallery of Art in Washington, DC. Aristolochia species are hosts for the pipevine swallowtail, and so the gardeners in the Haupt and the nearby Mary Livingston Ripley Garden have been growing them for several years now, in order to attract the butterflies. Smithsonian Gardens has some wonderful spaces around the Mall, but I’m digressing.

UPDATE 8/22/18: The second butterfly is NOT a spicebush swallowtail. I failed to see something obvious. Pictured is the almost-identical red-spotted purple (Limenitis arthemis).


I checked many resources for help understanding butterfly identification; particularly useful sites included

Joe-Pyes Bring Big Butterflies

I closed last Wednesday’s post with a picture of a monarch butterfly on joe-pye weed, but that’s not the only butterfly I’ve been seeing around. Seems my little garden attracts quite a few types of butterflies, mostly because of the joe-pye weeds, but also because of some other plants. More on that in upcoming posts.

The camera had been on a tripod while I tried to get close-up shots of various flowers, but there was so much activity I finally gave up for awhile; taking the camera in hand, I started shooting butterflies instead.

This is a female eastern tiger swallowtail (Papilio glaucus), easily identified because nothing else in Maryland looks quite like it, with one exception: the Appalachian tiger swallowtail (Papilio appalachiensis), which is uncommon, only found in the western half of the state, and only flies from late April to early June.

The eastern tiger swallowtail is common and widespread in Maryland, flying in early May and again in August. Many types of trees can host the caterpillars, including wild cherry, sweet bay magnolia, and birch, each of which are growing not far from the joe-pye weeds in my garden.

The adults feed on a variety of flowers, sipping nectar through long proboscises.

The specimen pictured here is a female. The identifying characteristic is the blue spots on the hindwing; males have very little, or zero, blue on them.

Before wrapping up for the day I also took some shots of this dusky beauty. I was so happy, sure that I’d gotten a spicebush swallowtail. After all, there are several spicebushes nearby, so makes sense, right?

Yes, it makes sense, but I was wrong. This is not a spicebush swallowtail. More about that next time.

 

Bonus picture: cabbage white (Pieris rapae), I think.

 

 

 

Second bonus picture: the day after I finished writing this post, I spotted a male eastern tiger swallowtail. I had the wrong lens on the camera and the darned thing never stayed still; this is the best picture I could get. Note that there’s only a tiny amount of blue and orange spotting on it.

Bouncing Back

large-flowered leafcup

Interrupting my series on astery things and butterflies for a quick update on the Potomac Gorge, where I went this past Tuesday. After all the flooding, many plants are coming back. They aren’t as tall as they normally would be at this time of year, and some of them are just starting to bloom or bud up, a month or two late.

On the riverbanks, large-flowered leafcup (Smallanthus uvedalia) and cut-leaved coneflower (Rudbeckia laciniata) are blooming. A few New York ironweed (Vernonia noveboracensis) are also growing, looking short but with lots of buds.

cut-leaved coneflower

Right by the water’s edge, a few halberd-leaved rosemallow (Hibiscus laevis) are up, at about one-third of their mature height. I found one just starting to form buds; in other years, these plants started blooming in mid July.

buttonbush

In one place I saw an exceptionally short and shrubby-looking buttonbush (Cephalanthus occidentalis) with a few flower heads just formed, one with buds that will open any day now. In this area they usually start blooming in late June or early July.

woodland sunflower

Inland where there wasn’t any flooding, some of the typical mid-to-late summer bloomers are starting: two species of thoroughworts (Eupatorium) and goldenrods (Solidago) with buds just about to burst.

Starry campion (Silene stellata) and woodland sunflower (Helianthus divaricatus) are in full bloom. There were just a few blooms left on a stand of St. Andrew’s cross (Hypericum hypericoides).

cranefly orchid

And much to my delight, cranefly orchid (Tipularia discolor) is out.

Astery Things #2: The Joe-Pye Weeds

Eutrochium fistulosum

Once upon a time there was a genus of plants called Eupatorium. It was a large genus, lumping together plants commonly known as thoroughworts, bonesets, mistflowers, snakeroots, and joe-pye weeds. Roughly twenty years ago, the genus was split into twelve or more genera. Thoroughworts and bonesets are still Eupatoriums; mistflowers are now Conoclinium, and snakeroots Ageratina. Joe-pye weeds, those plants with large arrays of pink-purple flowers and whorled leaves, were placed in the new genus Eutrochium.

Eutrochium maculatum

Historically, four of North America’s five Eutrochium species were found in Maryland, but one of them, E. maculatum (spotted joe-pye weed), has been extirpated. The other three are

  • E. dubium (eastern or coastal plain joe-pye weed)
  • E. fistulosum (hollow joe-pye weed, trumpetweed)
  • E. purpureum (sweet, sweet-scented, or purple node joe-pye weed)

Distinguishing these four species from one another is fairly straightforward, provided you can look at mature, flowering specimens. Here is a much abbreviated chart of some identifying characteristics, taken from the Flora of North America, with the most useful ones in bold purple:

  E. dubium E. fistulosum E. maculatum E. purpureum
stems
purple-spotted purple purple spotted dark purple at nodes
  sometimes solid purple sometimes spotted sometimes solid purple greenish to purple-green
  solid hollow solid; may be hollow at base solid; may be hollow at base
leaves
arrangement in whorls of 3-4 in whorls of 4-6(-7) in whorls of (3-)4-5(-6) in whorls of 3-4(-5)
venation 3-nerved pinnately veined pinnately veined pinnately veined
shapes deltate-ovate narrowly lanceolate lance-elliptic lance-ovate
  ovate broadly lanceolate lanceolate ovate
  lance-ovate lance-ovate deltate-ovate
margins coarsely serrate finely serrate sharply or doubly serrate coarsely serrate
bases abruptly contracted gradually tapered gradually tapered gradually tapered
or abruptly tapered or abruptly tapered
florets
number (4-)5-9(-10) (4-)5-7 (8-)9-20(-22) (4-)5-7(-8)
notes
found only in coastal plain over 6 feet tall wide distribution known to hybridize
  and inland along major rivers morphologically variable morphologically variable

When trying to identify plants in the field, remember to look at the totality of characteristics rather than focusing on one or two, because there can be so much variation from plant to plant. And also because you really shouldn’t be cutting into plant stems in the field, at least not in areas where plants are protected.

E. fistulosum: hollow stem

Here are a few pictures to illustrate. Keep in mind that these are garden plants; wild-growing specimens rarely look so lush and full. Also, the E. maculatum pictured in this post is not the species, but rather a cultivar (‘Gateway’). Still, it’s not too far off what a wild plant looks like.

E. fistulosum: a whorl of 4 broadly lanceolate leaves

E. fistulosum: a loose corymb of flower heads

 

 

 

 

 

 

 

 

 

 

 

 

 

 

E. maculatum: whorl of three leaves, purple-spotted stems

 

And here are a few of E. maculatum. It’s worth noting that further up on the stems, the leaves were in whorls of four (but I couldn’t get a good picture up there).

E. maculatum: lanceolate-ovate leaf

 

 

 

 

 

 

 

 

 

Eutrochium species with purple node

This picture from four years ago is probably of E. purpureum, though I was never able to get close enough for a confident ID. At any rate, it shows what a purple node looks like.

 

Of course none of this is what makes joe-pye so interesting. It’s those flowers. Unlike the aster I wrote about in the last post, joe-pyes have no ray florets – only disc florets. Each floret consists of five pointed petals, fused at the base, from which a single long style emerges. The cumulative effect of all those tiny flowers, from 4-24 per head, dozens of heads in each corymbiform inflorescence, up to a dozen inflorescences on each stem, often multiple stems from one plant… it’s just breathtaking.

And then there’s the icing on the cake: joe-pye weeds attract bees and butterflies like crazy.

More about this next time.

 

Astery Things #1: New England Aster

Symphyotrichum novae-angliae is a typical aster, with flower heads consisting of roughly 50 to 75 dark rose to deep purple ray florets ringing a button of 50 to 110 disc florets that are initially yellow but become purple with age.

upper stem leaves

There are quite a few other blue-purple flowering aster species in Maryland, but distinguishing them is a topic for an upcoming post.

flower heads forming

This species is found mostly in New England, of course, and in the upper mid-west and mid-Atlantic, but also ranges south through the Appalachians and into the Great Plains. In scattered areas of the West it’s found as a garden escapee. In Maryland, New England aster is found almost entirely from the Piedmont west, with just a few occurrences in the Coastal Plain.

pruned by rabbits!

The flowers pictured here are typical, but this particular plant is not. Usually New England aster sports one stem (or just a few) standing up to four feel tall; there may be some branching near the top. The plant shown here was pruned several times by rabbits before I got ’round to spraying repellent on it, hence the short, bushy appearance. New England aster grows in a variety of habitats, sunny to partly shady, almost always in moist to wet soils.

 

Clearly it makes a lovely garden plant if you can protect it from herbivory while it’s still small.