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

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.

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
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
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
number (4-)5-9(-10) (4-)5-7 (8-)9-20(-22) (4-)5-7(-8)
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.


A Few Random Pictures

Seen recently along the C&O Canal and Potomac River in Montgomery County. I’m still posting pictures instead of writing…

Green heron (Butorides virescens). Picture taken with 24-70mm lens. I bought a 70-200mm lens a week later. But no matter how long a lens you get, it’s never enough.


Look at all the algae on the canal!





Damselfly. I’m not sure which species. Not even sure which family.





Monarch butterfly (Danaus plexippus) on a smartweed (Persicaria, species to be determined).