Damselfeast 2015

The Rambur's Forktail damselfly (Ischnura hastata) is one of the more widespread and common damselflies in my area, and across the southern part of the country, really. Its range even extends into Hawaii, according to the sightings map from Odonata Central:
Range of Rambur's Forktail in the United States. Map courtesy of Odonata Central.

Range of Rambur's Forktail in the United States. Map courtesy of Odonata Central.

There are a couple of reasons this damselfly has such an extensive range. One is that they are fairly large, dwarfing their relatives, especially the tiny Citrine Forktail (I. hastata) or the equally dainty Everglades Sprite (Nehalennia pallidula). Another reason might very well be that they are badasses! I was sitting on the couch one lazy afternoon while the wife and kids were at the library when I noticed an Everglades Sprite drifting near the doorknob of one of the French doors that lead out onto the pool deck. I ran into my office to get my camera, but by the time I got back, a female Rambur's had taken notice of this Everglades Sprite as well. And here is what ensued!
What lovely eyes, you have. Come closer, my dear, that I might see them better.

What lovely eyes, you have. Come closer, my dear, that I might see them better.

Your neck seems tight. Here, let me adjust it for you.

Your neck seems tight. Here, let me adjust it for you.

Whoops! Sorry!

Whoops! Sorry!

Well, there's no putting the milk back in the bottle.

Well, there's no putting the milk back in the bottle.

Mm-mm! Good to the last bite!

Mm-mm! Good to the last bite!

The first two pictures were overexposed because I had left the camera in "bird" mode,1 which means wide open lens. Adding flash to that means the pictures were almost solarized. Good thing digital processing is so powerful; you can at least see the action! Here is a bit more about the species, for those who are interested. Like the range map above, this is from Odonata Central:
Rambur's Forktail is the most widespread forktail of the New World, ranging as far north as Maine, southward to southern California, Mexico, Central and South America. . . . It also inhabits the Hawaiian Islands, where it was introduced in 1973. . . . As widespread as this species is, surprisingly little has been written about its biology. Both sexes will remain close to the water and although males are not territorial, females are known to be highly predaceous and often cannibalistic. Males often do not release females from the wheel position for several hours, and sometimes as many as seven, to secure their genetic contribution. Red females will sometimes attack males, but more often curl their abdomen downward while fluttering their wings in a refusal display.
I bring to your attention the relevant bit from the description above: "females are known to be highly predaceous." As the Everglades Sprites attempting to get their mack on just a few feet away might say, "tell us about it!"
A pair of Everglades Sprite attempting to seal the deal just two feet away from one of their brethren being eaten by a Rambur's Forktail. Survival of the fittest, indeed!

A pair of Everglades Sprites attempting to seal the deal just two feet away from one of their brethren being eaten by a Rambur's Forktail. Survival of the fittest, indeed!

References Odonatacentral.org Paulson, D. (2011). Dragonflies and Damselflies of the East. Princeton, NJ: Princeton UP.

Dragonflies and damselflies returning to the yard

After a dry beginning to March (and no rain since then, but at least the heat's moderated a bit for the past few days), the odonates have started returning to the yard, just in time for the equinox! One or two of them run into mishaps:
Watch where you fly! Halloween Pennant (Celithemis eponina) served up for breakfast to a spiny-backed orb weaver (Gasteracantha cancriformis). Boca Raton, FL, March 18, 2015.

Watch where you fly! Halloween Pennant (Celithemis eponina) served up for breakfast to a spiny-backed orb weaver (Gasteracantha cancriformis). Boca Raton, FL, March 18, 2015.

but by and large they are still the most formidable airborne insect predators out there. Most of them sprint to safety as I approach, although the Blue Dasher is often more docile,
Blue Dasher (Pachydiplax longipennis). Boca Raton, FL, March 19, 2015.

Blue Dasher (Pachydiplax longipennis). Boca Raton, FL, March 19, 2015.

as is a chilly Eastern Pondhawk in the early morning:
Eastern Pondhawk (Erythemis simplicicollis). Boca Raton, FL, March 20, 2015.

Eastern Pondhawk (Erythemis simplicicollis). Boca Raton, FL, March 20, 2015.

The smaller and daintier damselflies are generally more approachable with a camera even after the sun has warmed them up a little; after the "chill" of the morning burns off, most of my dragonflies sprint away as I approach. Damselflies, on the other hand, sit still so you can sneak up on them. And, if you look at the bottom of the photo below, other creatures have little difficulty approaching as well.
Rambur's Forktail (Ischnura ramburii). Boca Raton, FL, March 20, 2015.

Rambur's Forktail (Ischnura ramburii). Boca Raton, FL, March 20, 2015.

Since I didn't notice the spider until after I'd come inside to view the photos on the screen, I have no idea what kind it is. Presumably a flower spider of some sort; it's quite small, given that the damselfly is no colossus itself. Happy first day of spring!

After the rains, the odonates appear

South Florida is typically described as having two seasons: wet (May through October) and dry (November through April). Hydrologists like to split this up a bit further, with the wet season (now called high rainfall, low evapotranspiration season) running June through October, and the dry season now divided into two subseasons: low rainfall, low evapotranspiration (November through February) and a low rainfall, high evapotranspiration season (March through May). What this translates to in layman's terms seems to be something like "wet, then dry, then really dry." Over the last three years, two Aprils have been fairly wet (7.5 inches at my rain gauge this year, and a whopping 9.22 inches the previous year), while one was quite dry (in 2011 we had only 1.15 inches of rain in April). This year, May started off with a bang: Over six inches of rain in the first three days, five and a half of them in one long rainy day that also included at least one tornado here in Boca Raton (at my dentist's office, no less!). All that moisture falling from the sky, saturating the local soil, has an effect on wildlife. Saturday morning, after what seemed like forever, the yard was full of odonates again. Damselflies (Rambur's Forktails, Fragile Forktails, and Everglades Sprites) and dragonflies both (Blue Dasher, Little Blue Dragonlet, Eastern Pondhawk) were flitting around in the tall grass (after months without having to mow, I can see that I'll be back out on a weekly basis with my trusty reel mower—no gas for me!). Here's a shot I liked of one particularly patient Everglades Sprite (Nehalennia pallidula):
Everglades Sprite (Nehalennia pallildula). Boca Raton, FL, May 4, 2013.

Everglades Sprite (Nehalennia pallildula). Boca Raton, FL, May 4, 2013.

As usual, you can click on the image for a larger view. If you look closely, you can see the individual facets in the right eye:
Everglades Sprite (Nehalennia pallildula), detail. Boca Raton, FL, May 4, 2013.

Everglades Sprite (Nehalennia pallildula), detail. Boca Raton, FL, May 4, 2013.

As you may recall, those individual facets in the compound eye are called ommatidia. These tiny simple lenses, in combinations of hundreds (in the simplest compound eyes) to tens of thousands, form a complete image in the brain of the animal. The more ommatidia there are, the greater the visual acuity of the animal in question (in addition to insects, millipedes and mantis shrimp have compound eyes featuring ommatidia). In that respect, they function very much like the pixels on a CCD chip: as you add more pixels to your camera, you can create larger and larger images at high resolution. (Can you tell I got a new camera recently? One with a ridiculously high pixel count?) Another damselfly appeared a bit after I got tired of chasing those sprites around. This one is a Fragile Forktail (Ischnura posita):
Fragile Forktail (Ischnura posita). Boca Raton, FL, May 4, 2013.

Fragile Forktail (Ischnura posita). Boca Raton, FL, May 4, 2013.

And there was the ubiquitous Rambur's Forktail as well:  
Rambur's Forktail (<i>Ischnura ramburii</i>). Boca Raton, FL, May 4, 2013.

Rambur's Forktail (Ischnura ramburii). Boca Raton, FL, May 4, 2013.

Here's the first dragonfly I've managed to image so far this month; the Blue Dasher (at one point the most commonly photographed odonate on odonatacentral.org):
Blue Dasher dragonfly (Pachydiplax longipennis). Boca Raton, FL, May 4, 2013.

Blue Dasher dragonfly (Pachydiplax longipennis). Boca Raton, FL, May 4, 2013.

And here's the second. (Surprise, surprise! Another Blue Dasher):
Blue Dasher (Pachydiplax longipennis. Boca Raton, FL, May 4, 2013.

Blue Dasher (Pachydiplax longipennis. Boca Raton, FL, May 4, 2013.

And the third, a different species this time (Little Blue Dragonlet):
Little Blue Dragonlet (Erythrodiplax minuscula). Boca Raton, FL, May 4, 2013.

Little Blue Dragonlet (Erythrodiplax minuscula). Boca Raton, FL, May 4, 2013.

If this keeps up, it might be an interesting season for backyard wildlife after all!

A romp in the grass with some fine damsels

ischnura_ramburii_wheel_20120424
The last few days have seen the finest weather I can recall since moving to Florida. Daytime highs in the low- to mid-70s, overnight lows in the 50s and 60s, a light breeze making sure that even when you're out in the sun you feel cool and refreshed. This is what living in south Florida is supposed to be like! When the weather's this nice, one of my favorite things to do during my lunch break is go out and get dirty. And every now and then, getting dirty involves rolling around in the grass chasing after lovely little damsels. And every now and then, when you chase lovely little damsels you catch them. Here are some pictures of the lovely little damsels I caught during my lunch break one day this week. A beautiful, if somewhat immature, female Citrine Forktail (Ischnura hastata): Doesn't she have just the loveliest orange color all up and down her body? Were she older, her color would be a bit duller: her abdomen would have blackened up and perhaps become pruinose (powdery/waxy white), her thorax (including her eyes) would have become greenish, and she'd generally look a little less like a bright orange/red sports car. The next day I saw her, or perhaps her sister or cousin, in the front yard: Still beautiful, right? This is more likely a sister or cousin, as our original little girl didn't have any nasty mites on her underbelly, and you can see in the picture above that this little lady has acquired such a hitchhiker. My understanding is that these mites are typically acquired during the damselfly's larval stage, and they just sort of hang around until they can begin feeding on the adult form. Next, illustrating the fact that nothing in the world escapes the indignity of being eaten, whether it will or no, two different forktails, a male Citrine and a female Rambur's are both dining and being dined upon. Reminds me of "Bugs" by Ogden Nash:

Some insects feed on rosebuds, And others feed on carrion. Between them they devour the earth. Bugs are totalitarian.

—Ogden Nash

See the little mites under the thorax of this male Citrine Forktail? They probably bug him a little bit, but from all accounts, unless they are quite numerous they don't seem to measurably affect his quality of life. April must really be the month for Citrine Forktail here in Boca; my yard has been veritably plagued by them for weeks now (if you can call the presence of beautiful little insectivorous fliers a plague). Just to show how many there were, here are a male and immature female jockeying for space on the same wildflower/weed in my front yard: And now, toward the end of the month, their larger cousins, Rambur's (I. ramburii) are showing up as well: The female in the picture above has captured a nice juicy prey item (looks like a leafhopper) and is happily munching away at it, all the while being happily munched upon in her turn by those leetle tiny mites on the right side of her thorax. (It's thought that, like the lice on birds, the mites on each species of odonate are separate species. Can you imagine how abundant parasite species must be, if there's at least one separate species for each host species on the planet? One study of just one type of parasite (gregarines, one-celled protozoans) demonstrated that these organisms tend to be host-specific as well, so when you add up the number of kinds of parasites, then multiply by the number of known species of hosts, you're dealing with astronomical quantities.) The female of Rambur's Forktail is polymorphic, which means that she comes in more than one color form (but only one per customer, please). The individual pictured has what is known as andromorph coloration (from Greek andro-, "male"); that is, her color is almost exactly like that of the male. Her thorax, though, unlike the green thorax of the male, is blue. This color difference means that she is technically immature; if she were older, it would be green just like the male's. How can I prove that she's female? Well, today it was pretty easy: she's the one on the bottom in the wheel, or heart, position: Why on earth, you might ask, do these damselflies have to resort to such an odd position for copulation? Well, you see,
Male Odonata are unique among exopterygote insects [ie, those that undergo incomplete metamorphosis, with only egg-larva-adult stages of life, rather than complete metamorphosis, egg-larva-pupa-adult] in having the primary genital orifice and the intromittent organ located at opposite ends of the abdomen. (Corbet 1999)
During copulation, the female's tail tip is pressed up against a secondary genital structure located between the male's second and third abdominal segments. That structure, called the seminal vesicle, has been packed  with sperm from abdominal segment 9, right near his own tail tip—how he manages to first clasp the female and then transfer the sperm would be a complete mystery to me were it not for the helpful illustration from Corbet that I reproduce below—and is being pressed up against the female's tail tip so the sperm can be transferred from said vesicle to her spermatheca; any eggs that pass through that spermatheca then become fertilized. Here is a graphic representation of the process from the dean of odonate studies, Philip Corbet (you have to click the image to see all 8 stages; the thumbnail cuts the picture off mercilessly): The process looks inordinately complicated to our anthropocentric eyes, but it's worked for odonates, both damsel- and dragonfly, for millions of years longer than primates have been wandering the earth. And here, just because they came out nicely, are a couple more shots of the beautifully colored male Citrine Forktail: References Corbet, P.S. (1999). Dragonflies: Behavior and Ecology of Odonata. Ithaca and NY: Comstock. Paulson, D. (2011). Dragonflies and Damselflies of the East. Princeton, NJ: Princeton UP.