Step into my parlor…

...said the spider to the lady beetle. And yet, nothing happened. This morning before work I went out and, as usual, was taking pictures of whatever I could find in the yard. I found this lovely Southern Sprite damselfly (first of the season):
Southern Sprite (Nehalennia integricollis). Boca Raton, FL, May 8, 2015

Southern Sprite (Nehalennia integricollis). Boca Raton, FL, May 8, 2015

It's always a pleasure to see these relatively rare damselflies. (Odd, too, how abundance is so tied to locale: Everglades Spite (N. pallidula) is considered very rare, while Southern Sprite isn't, and yet I get dozens and dozens of the former over several months and very very few of the latter. I guess being near the Everglades is conducive to the occurrence of Everglades Sprite? While most people across the range of these insects are not near the glades...) When I was finished with the sprite's photo session I wandered over to the patch of dune sunflower I have growing along the drive. I noticed one flower had two petals sort of curved upward toward each other, indicating, most likely, the presence of a hunting spider. (That is, a spider that hunts without using a web.) It had tied the petals together with a strand of silk; you can see them curling up toward the camera in the photo below:
Thomisid spider waiting for breakfast. Boca Raton, FL, May 8, 2015.

Thomisid spider waiting for breakfast. Boca Raton, FL, May 8, 2015.

Thomisid spiders are commonly known as "crab spiders" (not to be confused with Gasteracantha cancriformis, commonly known in south Florida as a "crab spider," although most naturalists call it the spiny-backed orbweaver to avoid confusing it with the "true" crab spiders like the one above). The true crab spiders are so called because their front pairs of legs are drastically elongated, much like the pincers of a crab. It's one of the largest spider families, with over 2,000 species worldwide. There are at least 130 species in 9 genera in the United States, so identification to species level is left to the true spider experts, the araneologists (as distinct from the arachnidologists, who study arachnids in general, which includes arthropods from other orders such as scorpions, mites, ticks, and chiggers, in addition to the Daddy Longlegs, which aren't true spiders at all). While I was taking pictures of this unusual flower-trapping arrangement (normally I see the petals of the flowers curled down, rather than up), I noticed a wee little lady beetle about to become breakfast:
Lady beetle, meet spider. Boca Raton, FL. May 8, 2015.

Lady beetle, meet spider. Boca Raton, FL. May 8, 2015.

And then the strangest thing happened: the spider just remained motionless while the beetle climbed on the spider's back, tumbled off onto the disk portion of the flower, and then scurried away out of sight!
Let's make a closer acquaintance.

Let's make a closer acquaintance.

So long, and thanks for stopping by. (The beetle is visible to the lower left of the spider.)

So long, and thanks for stopping by. (The beetle is visible to the lower left of the spider.)

I wasn't able to snap a picture of the scene as the beetle left, but I was certainly surprised to see what I assumed would be a typical predation scenario turn into nothing at all. In case you're curious, the lady beetle looks very much like the "metallic blue" lady beetle, Curinus coeruleus, although it's by far the smallest one of them I've ever seen. References Marshall, S., & G.B. Edwards. 2008. Florida’s Fabulous Spiders, 4th ed. Hawaiian Gardens, CA: World Publications. Ubick, D., P. Paquin, P. E. Cushing, & V. Roth (eds.). 2005. Spiders of North America: An Identification Manual. Keene, NH: American Arachnological Society.

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.

Everglades Sprites all over the place

nehalennia_wheel_20120603
After my post a couple of weeks ago where I lost track of a pair of damselflies in tandem before I found out whether they actually attained the wheel position I've been hoping for another chance. Today, the first sunny day after what seems like a week of rain, I got my wish. In spades! This evening there were more Nehalennia pallidula than I could shake a stick at! Everywhere I looked was a male looking for a mate, a pair that I accidentally separated with my clumsy walking through the tall grass, or a pair actually mating! I managed to latch onto one pair that seemed to know which end was up, and I was able to follow them without scaring them to separate. I even managed a few "in-process" pictures. Here is one of the puzzles from last time; I simply couldn't figure out how the male grabs onto the female and THEN transfers the sperm from his primary genitalia at the tip of the abdomen to his secondary genitalia on segment two. Well, here is how he does it: Once the sperm transfer is complete, the male then induces the female to curl her abdomen up, as seen in the blurry image below: And then they are able to complete the wheel position. (Yes, many commentators have pointed out that this looks more like a heart than a wheel. Biologists don't care.) This species may not be abundant in the wild*, but in the urban wilderness of my property, I would guesstimate, just ticking them off on my fingers, that there were at least two dozen individuals today: 8 in the tall grass behind the shed, 5 or 6 more under the canoe, at least 6 more in the front yard, and probably 10 more on the other side. These are conservative guesstimates. These numbers are just for the Everglades Sprite; I didn't even mention (until now) the Fragile Forktail or two that I saw, or the Rambur's Forktail pair I saw mating earlier today. Don't know where all the Citrine Forktails have gone (a month ago they were present in numbers similar to those of the Everglades Sprite today), but their position in the ecosystem has not gone unfilled! Spring may be almost over, but it sure is still la saison d'amour here in my yard! Go odonata! *I know no one ever clicks links anymore, so I'll just tell you that its status is "Near Threatened" on the IUCN Red List for 2011.2.

New Backyard Bug: Nehalennia pallidula

nehalennia_pallidula__tandem_20120515

Damselfly behavior notes: Everglades Sprites in tandem

Part of the fun of documenting the presence and behavior of the animal and plant species in your back yard is the opportunity to contribute, in however slight a way, to an improved understanding of our world. My "study site," which is my 1/4-acre property in downtown (but basically suburban) Boca Raton, is small enough that most of the animals come and go, and while I welcome those that come, I can't follow them when they go. That means that for most of the organisms I write about on this blog, I take a few snapshots, do a little book research (often in 18th- and 19th-century taxonomic catalogues that are now available online thanks to Google Books), and that's about it. I wave goodbye to the species and hope to encounter it again someday. But I've always wanted a richer, deeper encounter, one where I can see how this animal actually behaves. A couple of weeks ago, I got a taste of this kind of observation, when I was lucky enough to observe a pair of Rambur's Forktail damselflies (Ischnura ramburii) copulating on one of my young Bitterbush plants. This week I got another, more prolonged encounter with another species, Nehalennia pallidula, aka the Everglades Sprite. I happened to observe a pair in tandem as I was doing my daily perimeter patrol with camera. This is a species for which as recently as 1990 the mating behavior was completely unknown (Dunkle 1990). Since that time, more has been discovered, enough so that Paulson (2011) is able to write about the timing of sightings of mating pairs, but it's still kind of fun to be able to add to the behavior accounts of a little-known animal. It's been decades since I wrote a biology report, but I was inspired by this event to try my hand at it; I apologize for the rather dry nature of the rest of this post, but it was a lot of fun for me to write. And I stuck in a lot of pictures, so I hope that'll make it interesting enough for y'all! Date: Tuesday, May 15, 2012. Time: 9:45–11:05 a.m. EDT. Weather: Partly cloudy, intermittent light rain in area. 81°F, 30.02 mm Hg at start, 83°F, 30.03 mm Hg at finish. Site information: Small suburban backyard in Boca Raton, FL (26.35691°, -80.09095°) with water present (not a viable oviposition site, as it is a well-maintained swimming pool, although there may be standing pools of water in neighboring properties). Vegetation includes numerous herbaceous forbs, grasses, vines, and woody plants approximately 1.5 m south of a wooden 1.6-m tall privacy fence, and 2 m north of a 1.25-m tall mesh pool safety fence. The ground slopes down approximately .75 m between the two fences, which are separated by about 3.5 m. Five zygopteran species have been recorded on the site: three forktails (Ischnura ramburii, I. hastata, and I. posita), a bluet (Enallagma sp., likely doubledayi), and a sprite (Nehalennia pallidula). Observations During the past two weeks the site has been visited by several zygopteran species, including at least 4 individuals of Nehalennia pallidula. Rain has become more frequent and intense in the past four days, and today, during my daily inspection of the property, at 9:45 a.m. EDT I observed a pair of Nehalennia pallidula (Calvert, 1913) perched in tandem on the inflorescence of a 1 m2 Heliotropium angiospermum; small runners of the vine Passiflora incarnata were growing intertwined with the plant as well. The damselfly pair was motionless for some time, but took flight as I approached closer (approx. 0.5 m). The pair flew to a different perch nearby, this time on a nearly vertical, and fairly slender, stem of P. incarnata. They remained there for some time (I estimate >10 min, but I did not have a watch with me, so was relying on the time stamp of my digital camera), during which time the male flexed the tip of his abdomen rhythmically about once every second, thereby swinging the female, presumably in an attempt to bring her into the copulatory position (Stage D of Corbet's diagram). In this image you can see that the male's tail tip is strongly flexed, and the female's tail tip is blurred by the motion, but her abdomen is straight: The swinging was relatively rhythmic, approximately once per second for approximately one minute, followed by a shorter (<30 seconds) rest period, after which the male resumed flexing the abdomen. This flex–rest cycle happened five times, throughout which (and indeed throughout the encounter) the female remained with abdomen rigid and legs tucked under the thorax. At one point the female fluttered her wings, but the male was not induced either to release her or to move to a new perch. The male's wings were observed to be held slightly spread, rather than folded together over the back as in the normal (horizontal) perching position. Presumably this allows greater stability to support the weight of the female while perched in tandem. The female's legs are folded up tight to the thorax, presumably to minimize drag in case the male needs to move the perch. After about 10–15 min, a lizard moved close to the pair, after which the pair changed perches 3 to 4 times in less than a minute before settling back on another stem of Passiflora incarnata; this one quite a bit thicker than the first: They remained on this perch for some 3 minutes (until 10:02), after which I lost track of the pair and assumed they had left the area. I later (10:10) discovered that a single male Ischnura posita had come to occupy the part of the plant that the pair had briefly visited before disappearing: I assumed that the arrival of this individual had prompted the departure and perhaps even separation of the N. pallidula pair, as I later (10:36) noticed a lone female N. pallidula near the original site of contact. This female, however, seems to have been a different individual—the amount of black on abdominal segments 9 and 10 appears greater, and I am fairly sure that the female in the tandem pair did not have a mite on her thorax, while this lone one did (although the legs of the female in tandem were folded under the thorax, which prevented me from observing the presence or absence of mites): At 10:38 I found the tandem pair again and was able to observe them for another few minutes before I lost track of them again (at 10:42). I assume that they separated afterwards, because at 11:04 a.m., I observed a lone N. pallidula who closely resembled the female of the pair (at least, this individual's tail markings were very similar, and she did not have a mite on her thorax). Discussion In 1990, Dunkle wrote that the biology of this species was unknown; Paulson, writing in 2011, was able to give some details about when mating pairs are seen (only after the rainy season has begun). While it's not clear that this pair did mate, it is evident, based on these observations, that tandem flight in N. pallidula lasts at least one hour, probably more. I did not observe copulation, although I was unable to determine whether it was because the female was immature or unwilling, or whether it did occur but during the time I was unable to observe the pair. Etymology As usual, I like to provide the etymology whenever I can. Nehalennia is a river goddess depicted on numerous votive altars from the area where the Rhine river flows into the North Sea. The English name for the genus is Sprites; according to Paulson and Dunkle's checklist, this name comes from the fact that "species are tiny and difficult to detect." The scientific name, pallidula, means "little pale," which, again according to Dunkle, refers to the "greater extent of pale color on sides of thorax than other Nehalennia." References Dunkle, S.W.  (1990). Damselflies of Florida, Bermuda, and the Bahamas. Gainesville, FL: Scientific Publishers. Paulson, D.R.  (2011). Dragonflies and Damselflies of the East. Princeton, NJ: Princeton UP. Paulson, D.R.  and Dunkle, S.W. (2012).  A Checklist of North American Odonata. including English Name, Etymology, Type Locality, and Distribution. Available online.