Last week I noticed a couple more damselflies; these guys were in the front yard instead of the back yard. The first two pictures are from Saturday August 20th: Everglades Sprite.]
This month the odonata population (dragonflies, anisoptera, and damselflies, zygoptera) seems to have exploded in Palm Beach County. We've had dozens of dragonflies patrolling our pool, (tonight it even looked like a few of them were trying, in a not very evolutionarily adaptive way, to lay eggs in it!). But we've also had a few of their daintier cousins, the damselflies, disporting themselves quite shamelessly. Here are a few snapshots of the damselflies. These Common Spreadwings were enjoying the foliage around our pool while their larger cousins, the dragonflies, were patrolling the airspace above the water (they were a bit shy, and the closest camera to hand was the one with the "normal," not telephoto, lens, so this was the best pic I got):
Wow, my first-ever Dragonfly Week is already drawing to a close, and I have so many more things I was going to write about! I had planned to at least mention some of the adaptations that go into the incredible aerial feats performed by these "primitive" insects, like their offset thorax, their wings (structurally, they have spars and struts to stiffen the otherwise flimsy "cellophane"; functionally, they have independent 4-wing drive, rather than the "paired" flight evolved by other insects, e.g., Lepidoptera and Hymenoptera; physiologically they have "what may well be the most massive mitochondria in the animal kingdom [Corbet 1999, 397]). But to really go into all of that, I'll have to do a lot more studying, which I just don't have time for right now! I had a lot of fun going through my photo files to find pictures for this week. Just doing that raised my dragonfly sighting list from 16 to 18, with the ID of my two unknowns from 2008: Twilight Darner from T.S. Fay, and the Slaty Skimmer from Fern Forest. So I thought I'd just share some of the cool things I found out about dragonflies this week, through photos. The image below, of Celithemis eponina (Halloween Pennant) illustrates the "four-wing drive" aspect of dragonfly anatomy. Insects where the hind wing is velcroed to the forewing would not be able to do the "splits" like this:
Going through my old photo files has been fun for me; last night I found a slightly better photo of
Coryphaeschna ingens, the Regal Darner [UPDATE:Gynacantha nervosa, Twilight Darner] who visited us during Tropical Storm Fay. I also ran across a couple of untagged photos of other species that I knew I'd seen, but couldn't find in my files (lesson: ALWAYS apply photo tags). One of the untagged photos that I found is this Common Green Darner (Anax junius) that I saw on one of my lunchtime walks at Fern Forest:
Regal Darner was also an aeshnid, but in a different genus.
The generic name of the Common Green Darner is Anax, which means king, lord, chief, master in Greek. Junius, I'm not so sure about, since it's not in my go-to source (Brown, 1956), but it looks like a straightforward nominative form of Iunius, which is Latin for June: that would mean this species name translates to "June ruler," presumably because it is so common in that month. It was described by Dru Drury in his 1773 Illustrations of Natural History.
According to Cannings and Stuart (cited in a natural history report from the Royal British Columbia Museum, which I found in the Wikipedia article on the name Aeshna), the family name Aeshnidae comes from a misprint of the Danish entomologist Fabricius's original name for the genus, Aechma, from the Greek word meaning "spear." That would mean the genus of yesterday's dragonfly, Coryphaeschna, is a compound word, formed from this word and another Greek word, corypho, "head, top": "spearhead." The French entomologist Jules Pierre Rambur described that species, the type specimen for the entire genus, in his 1842 Histoire naturelle des insectes, part of the Suites à Buffon.
I've not yet found any source to corroborate my speculations above, so if anyone knows where I can find out more, I'd appreciate hearing about it!
Brown, R.W. (1956). Composition of Scientific Words: A Manual of Methods and a Lexicon of Materials for the Practice of Logotechnics. Washington, DC: Smithsonian Institution Press.
Cannings, R.A. & Stuart K.M. (1977). The Dragonflies of British Columbia. British Columbia Provincial Museum Handbook No. 35, Victoria, B.C.
Catalogue of the Odonata of the world.
A two-year-old mystery has come closer to being solved, thanks to the friendly folks at bugguide.net. You see, back when Tropical Storm Fay blew into town on August 18, 2008, a large dragonfly took shelter on our porch:
The darners are long and slender-bodied, like a darning needle, and they include the largest Florida Dragonflies. Their eyes are very large and meet in a seam on top of the head. In most species scars can be seen on the eyes of a female where a male has held her during mating. Females have an ovipositor with blades, as in the Petaltails. Darners hang vertically on a perch whether it is a vertical stem or a horizontal twig [or in this case a brick-face wall]" (20).Unfortunately I wasn't aware of the importance of the thorax in distinguishing among several possible species in different genera, Comet Darner (Anax longipes), Cyrano Darner (Nasiaeschna pentacantha), and Regal Darner (Coryphaeschna ingens), but I'm pretty sure that this is the latter species. [UPDATE 9/10/10: Upon further review, it looks like Twilight Darner (Gynacantha nervosa) is a better match for this individual. The thoracic markings are indistinct, which fits G. nervosa much better than C. ingens.] In the first place, the friendly folks at bugguide.net think it's likely to be. In the second place, most of the photos I've seen of Comet Darners show "blotches" on the abdomen, rather than the "dots" I see on this one. Cyrano darner has those dots, but, according to the checklist from Odonata Central, has not been recorded in Palm Beach County, while Regal Darner has been. (Not that going by the book is a sure guide, particularly with a tropical storm that could be blowing things in from far away, but it's another piece of the puzzle.) Now, two years later, I sure wish I'd taken more photos, but at the time I was more concerned with putting the hurricane shutters on than I was with narrowing down the ID of the animal. I was pretty sure the photos I had would be conclusive. As it turns out, they are simply not good, from any angle, because I didn't know what I should have been looking for. That's why relying on photography for a positive ID is a problem: if the field mark you need is not in focus, you're out of luck. (On the flip side, it's a good learning tool: now I know to try to get good pictures of the thorax for any darner, so we can use the markings there to help figure out what it might be.) Here's the other side, of the animal, with a better view of the tail: like this one, you can see that they are quite long; the ones on this lady are pretty short. No, the ovipositor is a bit higher up, on the right of the picture (ventral, or bottom, side of the abdomen). [UPDATE 9/10/10: the ovipositor is above the last abdominal segment, 10; on that segment (S10), you can see, in Dunkle's words and in that photo of the tail, "2 spines on the underside...which are used during egg deposition. [They] form a fulcrum when she uses her ovipositor blades to lay eggs in soil" (28).] So don't get confused if you see a male dragonfly with terminal appendages. That's perfectly normal. A male dragonfly with an ovipositor, though—that would be big news. So, to make a long story short, if you want to take better nature photos, learn more about your subjects, so you can know what it is you're trying to capture. Then see if there's a way to make it pretty. I have a long way to go on both fronts... But it's a fun road to travel!
I think everyone likes to learn things. I know I do. Last week when I spotted a dragonfly perched in the oak tree out front, I grabbed my camera and binoculars to investigate a bit further. Perched Dragonflies are Much Easier to Identify than Flying Dragonflies. There are 169 species records in Florida now, but these include both the zygoptera (damselwings) and the anisoptera (dragonflies); I'm not sure what the breakdown between the two groups is. [UPDATE: According to this website, there are now 123 dragonfly species in the state, and 47 damselfly species, which brings us up to 170 as of 2007. Hmmmm.....] Back in 1989, when Sidney Dunkle published his groundbreaking field guide to the state, he included 86 dragonfly species (94 with Bermuda and the Bahamas included); I wonder if there have been enough changes to the list to require a new field guide to Florida? [John Epler's 123 species certainly seems to argue for an update.] Whichever number you like, 169 or 93, it's a tolerably round number for a group of insects that are as hard to chase down as odonates. Even though there are only seven families of dragonfly species in both Americas, I still can't separate many of them in the field even to the family level; it's only with a camera that I stand a chance. I'm trying to change that, little by little, by learning the species that occur commonly, so that I'll recognize anything new. (If anyone has a simple flight silhouette technique for sorting out, skimmers and darners at a glance, I'd love to buy it! The keys in my major reference works are either too complex, like the one in Garrison, Ellenrieder, & Louton, which includes all the genera of North and South America, or, if they're as straightforward as the one in Mitchell & Lasswell, it still requires that you have the insect in hand.) Part of my problem, I think, is that most of the species I see are members of the Libellulidae, the skimmer family. Large and diverse as it is, it's still only one of the seven families; it's pretty rare that I see other flight silhouettes at all! (Last Saturday at Yamato Scrub I got excited because I saw a silhouette I didn't recognize; turned out to be some kind of sphecid wasp.) If I don't often see the other silhouettes, I'll have a hard time learning them, won't I? (Guess I'd better get out in the field more often...) As you know, there are, according to Odonata Central, 53 distinct species in Palm Beach County. Here then, is a typical silhouette of a libelullid, or skimmer, as seen by me in a tree: Carolina Saddlebags, because of the large markings on the hindwing; they really do sort of look like the thing is carrying luggage back there! e first ever color photo guide to dragonfly species anywhere in North America: Violet-masked Glider. After all, that #1 linked-to page on the Carolina Saddlebags is to a website describing the dragonflies of New Jersey! I like that name better for a couple of reasons. One, it avoids the tendency that has fouled up the common names of birds for centuries, that being to name a species based on a location that it might or not occur in, just because that's where the first specimen was encountered. Two, it's descriptive. Whatever name they go by, though, they certainly are distinctive dragonflies; when I see these guys, I know I'm looking at a skimmer, probably a Tramea species, and I even have a good shot of telling whether it's a Carolina or a Red. It's a start! References Dunkle, S.W. (1989). Dragonflies of the Florida Peninsula, Bermuda and the Bahamas. Gainesville: Scientific Publishers. Garrison, R.W., Ellenrieder, N.V., Louton, J.A. (2006). Dragonfly Genera of the New World. Baltimore: Johns Hopkins UP. Mitchell, F.L. & Lasswell, J.L. (2005). A Dazzle of Dragonflies. Texas A&M UP.
My post about the Pierides the other day got me thinking of Alexander Pope's advice, in his Essay on Criticism: "A little learning is a dang'rous thing; Drink deep, or taste not the Pierian spring." Pieria was a region in ancient Macedonia, rather than Thessaly where Pierus and his daughters (the Pierides) lived. But Macedonia was where Mount Olympus was supposed to be, and the Muses (also called the Pierides after they pwned Pierus's daughters in the earliest episode of Ancient Greek Idol) hung out there. So Pieria might well have been named for the Muses, rather than the ancient tribe, the Pieres, or their country of Pieris, as the nonmythological histories would have it. In any case, I've decided to follow Pope's (not the Pope's) advice, and try to learn more about the insect life around me. I posted about butterflies last week, so I'm posting about dragonflies this week. (No, I'm not just giving them one week apiece and calling that "drinking deeply"; I'll be reading about them for months. But it will take a while to get Needham, Westfall & May through interlibrary loan, and we forgot to go to FAU tonight to get Corbet, so...) Anyway, as part of my project, I decided to find out how many dragonflies are likely to turn up in my area. It turns out that there are 53 recorded species of dragonfly in Palm Beach County, according to Odonata Central: Anax junius (Common Green Darner) Anax longipes (Comet Darner) Aphylla williamsoni (Two-striped Forceptail) Argia fumipennis (Variable Dancer) Argia sedula (Blue-ringed Dancer) Arigomphus pallidus (Gray-green Clubtail) Brachymesia gravida (Four-spotted Pennant) Celithemis eponina (Halloween Pennant) Celithemis ornata (Ornate Pennant) Coryphaeschna adnexa (Blue-faced Darner) Coryphaeschna ingens (Regal Darner) Crocothemis servilia (Scarlet Skimmer) Enallagma civile (Familiar Bluet) Enallagma doubledayi (Atlantic Bluet) Enallagma durum (Big Bluet) Enallagma pollutum (Florida Bluet) Enallagma vesperum (Vesper Bluet) Epitheca princeps (Prince Baskettail) Epitheca stella (Florida Baskettail) Erythemis plebeja (Pin-tailed Pondhawk) Erythemis simplicicollis (Common Pondhawk) Erythemis vesiculosa (Great Pondhawk) Erythrodiplax minuscula (Little Blue Dragonlet) Erythrodiplax umbrata (Band-winged Dragonlet) Gomphus minutus (Cypress Clubtail) Gynacantha nervosa (Twilight Darner) Ischnura hastata (Citrine Forktail) Ischnura kellicotti (Lilypad Forktail) Ischnura posita (Fragile Forktail) Ischnura ramburii (Rambur's Forktail) Ladona deplanata (Blue Corporal) Lestes vidua (Carolina Spreadwing) Libellula auripennis (Golden-winged Skimmer) Libellula axilena (Bar-winged Skimmer) Libellula incesta (Slaty Skimmer) Libellula jesseana (Purple Skimmer) Libellula needhami (Needham's Skimmer) Macrodiplax balteata (Marl Pennant) Macromia taeniolata (Royal River Cruiser) Miathyria marcella (Hyacinth Glider) Micrathyria aequalis (Spot-tailed Dasher) Nehalennia integricollis (Southern Sprite) Nehalennia pallidula (Everglades Sprite) Orthemis ferruginea (Roseate Skimmer) Pachydiplax longipennis (Blue Dasher) Pantala flavescens (Wandering Glider) Pantala hymenaea (Spot-winged Glider) Perithemis tenera (Eastern Amberwing) Stylurus plagiatus (Russet-tipped Clubtail) Tramea carolina (Carolina Saddlebags) Tramea lacerata (Black Saddlebags) Tramea onusta (Red Saddlebags) Triacanthagyna trifida (Phantom Darner) I'm pretty sure I've seen at least 16 (indicated in red above); I've photographed 8 or 9 of them (and failed to ID many of the ones I've photographed). I'd love to find more, but to do that, I have to start getting specific. Where am I likely to find a new species? We don't have too many rivers here in Palm Beach County, so if river cruisers require rivers, they'll probably have to wait until my next trip up to Riverbend Park. But we have plenty of canals; do those work? I'll have to find out. I get several different species at my house, many more at Yamato Scrub, and dozens at Fern Forest (down in Broward County); it's time to start getting more serious about this. I'm thirsty; time to head to Pieria!
There aren't a ton of animals visible in the steamy sunny heat of late June here in Boca; those few that there are, apart from the omnipresent mockingbird and his counterpart in red, the cardinal, tend to be insects. Here's a blue dasher dragonfly that seems to favor a perch on the spicewood tree on the side of our house: blue dasher page. The blue dasher is a widespread species in the United States, occurring from Florida and the Bahamas all the way out west to California, and north as far as southern British Columbia in the west to Ontario in the east. In other words, just about wherever you live in the lower 48, you have a good chance of encountering this species, although it is apparently absent from the Dakotas and the Rocky Mountain states. Apart from the lovely anisopterans, the other insect we get in droves here is one of Eric's favorites: butterflies! (He calls them lellerflies, as near as I can make out. He's not actually referring to the lepidopterans around here; his gymnastics lessons have him "reach for your butterflies"; i.e., reach your arms straight over your head, in preparation for "making your pizzas," which means planting your hands on the floor in front of you. All of this is to position you properly to allow you to turn a somersault. Just don't try it with real pizzas, please!) And here's a lellerfly in potentio, a Polydamas swallowtail (Battus polydamas): UF/IFAS web page; for many better photos, use bugguide.net. From the archives, here's another common caterpillar we get this time of year (although this archive shot was from December--while the summers can be a bit muggy, Florida winters are da bomb!): aposematic combination) would suggest. So go on, get out into the real world, even if it is a little hot, and a little muggy, and a little buggy. It'll do you some good!