Florida

T.G.I.Flyday—Black horse fly (Tabanus atratus)

/ Ted C. MacRae / 9 Comments

In my previous post, I talked about a day trip to a sand scrub remnant in the Lake Wales Ridge of central Florida to find and photograph the endemic Highlands tiger beetle (Cicindelidia highlandensis). Ironically, the dry sand scrub/pine woodland habitats along this ridge are dotted with small lakes and ponds, allowing a rich aquatic flora and fauna to co-exist alongside the xeric specialists. Field mate Chris Brown and I had found and just finished photographing the tiger beetles when we encountered this rather largish lake—bright, white sand surrounding crisp, clear water reflecting white, puffy clouds in a deep, blue sky. ‘Twas a spectacular sight, indeed!

Sand scrub lake

Sand scrub remnant, Lake Wales Ridge, central Florida

As we stood looking at the scenery, I noticed something black on the stem of one of the sedges growing along the water’s edge. Something big and black! As I moved closer I could tell quickly that it was a large horse fly, but it was not simply perched and resting on the sedge—there was something else going on. Moving closer, ever so cautiously so as not to disturb the fly, I eventually realized that it was a female in the act of oviposition. How cool—I’d never witnessed this before with any species of horse fly, so to see it with such a large species was a real treat. I recognized it instantly as Tabanus atratus—commonly called the black horse fly and recognizable as such by its large size, all-black coloration, and distinctively hooked antennae (see 3rd photo below).

Tabanus atratus ovipositing

A Tabanus atratus female oviposits on a stem overhanging the water.

Before we get to the eggs, let’s dispel some misinformation that seems to persist regarding the size of this species (as it does with almost any large insect). Black horse flies are undeniably large, and in fact they are one of the largest horse flies in North America. The more credible sources (e.g., Pechuman et al. 1983, Long 2001) cite body length as ranging from 20–25 mm (up to a full inch in length). Incredibly, the species does not take the honors as North America’s largest horse fly, which goes instead to Tabanus americanus and it’s upper limit of 30 mm (in fact, T. americanus may be the world’s largest horse fly)! There are, however, on-line sources and a few popular field guides (as cited in BugGuide) that state a maximum length of 28 mm for T. atratus. How credible this figure is I cannot say, but I guarantee that the size indications of 30, 40, and even a whopping 50 mm in length found routinely among photos of this species on BugGuide were not derived from careful measurement and almost certainly instead reflect the astonished reactions that such an abnormally large insect can generate! In fact, there are precious few insects in North America that reach lengths as grand as 50 mm (i.e., two full inches)!

Tabanus atratus ovipositing

Lateral view of oviposition.

We approached carefully, again so as not to disturb the female in the middle of her act, and we watched and photographed as she laid the individual eggs one by one, using the tip of her abdomen to carefully arrange them neatly against each other in stacked layers. From a photographic perspective, balancing flash exposure of the all-black adult with the bright-white egg mass presented a real challenge. Added to that was an additional exposure challenge (my desire for a blue-sky background), making it a truly difficult-to-photograph subject. Long (2001) states that T. atratus egg masses can contain anywhere from one hundred to a thousand eggs each, always near water’s edge or somewhere quite close to water. Females are capable of laying three or four of these egg masses, which apparently gradually turn dark as the eggs develop and approach hatch.

Tabanus atratus egg mass

Freshly laid Tabanus atratus egg mass.

Despite this being the first time I’ve ever witnessed oviposition by this species, it seems to be encountered regularly. There are several photos of ovipositing females among the many photos of this species that have been posted to BugGuide. Moreover, descriptions of the egg mass of T. atatus appeared very early in the literature, first by Hart (1895) and then in photographs by Schwardt (1936). The latter author also states “T. atatus deposits its eggs in masses which are so constant in structural plan as to make specific determination of the egg mass readily possible” (as quoted in Bailey 1948). Thus, even if this female had already finished and left her egg mass, it still could have been identified to species.

REFERENCES:

Bailey, N. S. 1948. Notes on Tabanus atratus subsp. nantuckensis Hine (Diptera). Psyche 55(3):131–138 [pdf].

Hart, C. A. 1895. On the entomology of the Illinois River and adjacent water. Illinois State Laboratory of Natural History Bulletin 4:149–273 [eBook].

Jones, C. M. & D. W. Anthony. 1964. The Tabanidae (Diptera) of Florida. U.S. Department of Agriculture, Agricultural Research Service, Technical Bulletin No. 1295, 85 pp. [pdf].

Long, W. 2001. Tabanus atratus (on-line), Animal Diversity Web. Accessed 20 March 2019 at https://animaldiversity.org/accounts/Tabanus_atratus/

Pechuman, L. L., D. W. Webb & H. J. Teskey. 1983. The Diptera, or true flies, of Illinois 1. Tabanidae. Illinois Natural History Survey Bulletin 33(1):1–121 [pdf].

Schwardt, H. I. 1936. Horseflies of Arkansas. Arkansas Agricultural Experiment Station Bulletin 332:14–15, 27–32.

© Ted C. MacRae 2019

 

Revisiting the Highlands tiger beetle (Cicindelidia highlandensis)

/ Ted C. MacRae / 12 Comments

In September 2016, I had the opportunity to attend the Annual Meeting of the Entomological Society of America in Orlando, Florida, which was being held in conjunction with the International Congress of Entomology. My first thought when I made plans to attend these meetings was that this would be a chance for me to get another look at the Highlands tiger beetle (Cicindelidia highlandensis). One of Florida’s rarest endemic tiger beetles, this species is restricted entirely to remnant sand scrub and pine woodland habitats along the Lake Wales Ridge of Polk and Highlands Counties in central Florida (Choate 2003). I was thrilled to have found adults (in good numbers) on my first attempt back in 2009, and I was also thrilled to have successfully managed to photograph the beetle at that time. However, in the years since, I have become increasingly dissatisfied with those photographs—taken during what was my very first year of insect macrophotography. I’ve learned a lot since then about lighting, diffusion, and composition, but perhaps the biggest annoyance of those photographs is the fact that in every one the antennae and/or legs are “clipped”—a result of my being so enamored with my newfound macrophotographic capabilities that I nearly completely ignored other aspects of photographic composition.

Chris Brown photographing Cicindelidia highlandensis

Chris Brown photographs a Highlands tiger beetle.

Chris Brown—long-time field accomplice and himself a tiger beetle aficionado and insect macrophotographer—was also at the meetings, and since he had never seen the Highlands tiger beetle before we made plans to slip away one day and visit the spot where I had seen them back in 2009. I knew our chances of finding them were slim—it was very late in the season (late September), and the species is a so-called “summer species” with peak of adult activity in July and August. We figured, however, that even if we didn’t find adults we would still enjoy the day in the field, and for some time after arriving at the site that’s all it was. Finally, in an open sandy area near a small lake we saw the first adult. I let Chris take his shots, as this was his first opportunity (see photo above), while I continued to search for additional adults. Eventually I found one and began the long process of “whispering” to it to coax it into allowing me the photographs I desired.

Cicindelidia highlandensis

Highlands tiger beetle (Cicindelidia highlandensis).

As you can see in the photograph above, my compositional preferences have changed since I took those first photographs back in 2009. In contrast to the “as close as possible” style that I initially adopted, I now prefer to back off from the beetle enough to include elements of the habitat in which it occurs. While this compositional style may show less detail on the beetle itself, I believe it adds perspective and results in a more interesting and aesthetically pleasing photograph. I also now like to get down as low as I can, often placing the camera directly on the ground rather than always shooting from “elbow-height”, for a more unique perspective of the beetle, and my use of better flash diffusion results in more even lighting and minimizes the distracting specular highlights that are often the hallmark of flash macrophotography.

Cicindelidia highlandensis

This individual demonstrates the thermoregulatory “stilting” behavior of the adults.

Sadly, my flash unit failed soon after I began photographing the beetle, which is a real shame because the beetle began demonstrating the characteristic “stilting” behavior that the adults use for thermoregulation in their hot environment. The photograph above is the only one that I could “rescue” through some rather heavy-handed post-processing to make up for the failure of the flash unit to fire (it is fortunate that I have shifted to routinely using a combination of ambient light and fill-flash rather than flash only, or I would have had not even this photograph to rescue!). I suppose this means I’ll just have to revisit this species once again (now that I have not one but two new flash units!), which isn’t all bad because I would also love to see and photograph once again the moustached tiger beetle (Ellipsoptera hirtilabris), another Florida endemic (or near so) that I saw here also during my first visit but not during this one.

The Highlands tiger beetle belongs to a group of species called the abdominalis species-group, with all four of the included species (C. abdominalis, C. floridana, C. highlandensis, C. scabrosa) occurring in Florida (three of which are endemic or near-endemic to Florida). For those interested, I have seen and photographed all four of the species and presented a “mini-review” with photographs and links to posts with more detailed information about each species, along with a key to the species to allow for their identification.

REFERENCES:

Choate, P. M., Jr. 2003. A Field Guide and Identification Manual for Florida and Eastern U.S. Tiger Beetles.  University Press of Florida, Gainesville, 224 pp.

© Ted C. MacRae 2019

Mother and daughter (perhaps)

/ Ted C. MacRae / 8 Comments

Phrynus marginenotata (Florida tailless whip scorpion)

Back in May I visited the California Department of Food and Agriculture’s Plant Pest Diagnostics Laboratory in Sacramento. While I was there to visit my friend and colleague Chuck Bellamy and see him receive Honorary Membership in The Coleopterists Society, I was also anxious for the opportunity to spend time with the lab’s other entomologists—most of whom I interact with as members of the Editorial Board of The Pan-Pacific Entomologist. Among the more ‘colorful’ of these is Martin Hauser, a dipterist (although I don’t hold that against him!) who also has a passion for maintaining live, captive arthropods. For me, there is nothing finer than visiting the lab/office of a taxonomic entomologist—one wall lined with steel cabinets full of insect specimens, another wall crammed-full of books and literature (the older the better), a workbench with microscope at the center of a jumble of specimen containers and open reprints, and shipping boxes piled everywhere. I take that back—there is nothing finer than visiting the lab/office of a taxonomic entomologist that also keeps livestock! Martin’s collection of live arthropods, however, goes well beyond the requisite 10-gallon aquarium with Madagascan hissing cockroaches. I already featured one of his more unusual tenants, Damon diadema (Tanzanian giant tailless whip scorpion), and here I feature its North American relative, Phrynus marginenotata (Florida tailless whip scorpion).

The genus is characterized by five spines on the pedipalp tibia—the 3rd shorter than the 2nd and 4th.

According to Weygoldt (2000), this is the northernmost and only U.S. representative of a mostly northern Neotropical genus of eleven species, recognized by the pedipalp tibia (the thickened segment of their “claws”) with five spines—the middle one shorter than the 2nd and 4th (refer to Photo 2). This species occurs in southern Florida and some Antillean islands, where it lives under coral stones and rocks close to the beach—a habitat that presumably subjects them to periodic flooding. While most tailless whip scorpions prefer humid/moist environments, they nevertheless studiously avoid standing water itself. This species, however, has been observed to voluntarily enter the water when placed on a stone surrounded by water and remain submerged for as many as eight hours. Remarkably, submerged individuals remain active and do not drown, apparently the result of a “plastron”—an area of the cuticle surrounding the lung openings that is packed with stiff, branched structures and, thus, capable of holding a volume of air against the body while the animal is submerged. The plastron seems to function much like a gill—oxygen continuously diffuses into the plastron from the surrounding water as it is used for respiration.

The bright orange pedipalps of 2nd-instar nymphs contrast with the somber coloration of the adults.

Like the D. diadema individuals that I also photographed, these P. marginenotata individuals had also produced viable eggs which had hatched a few weeks before my visit. Two nymphs can be seen with the adult in the top photo (although I can’t say for sure whether the adult is actually the mother), and Photos 3 and 4 show one of these nymphs up close and personal. I would have liked to have seen these nymphs when they first hatched, as the 1st-instars are a soft sea-green color and remain clustered on their mother’s abdomen until they are able to start fending for themselves (for a beautiful photo showing this, see Piotr Naskrecki’s The scariest animal that will never hurt you). The 2nd-instars that I photographed had already left their mother, and while they had lost their sea-green coloration, their pale yellow/gray bodies and bright orange pedipalps were no less striking compared to the more somber coloration of the full-sized adults.

…and, of course, the signature BitB face shot!

REFERENCE:

Weygoldt, P. 2000. Whip Spiders (Chelicerata: Amblypygi): Their Biology, Morphology and Systematics. Apollo Books, Stenstrup, Denmark, 163 pp.

Copyright © Ted C. MacRae 2012

Where siblings mingle: Ellipsoptera marginata vs. E. hamata

/ Ted C. MacRae / 14 Comments

When Erwin & Pearson (2008) formally broke up the great genus Cicindela by elevating most of its former subgenera to full genus rank, it caused a bit of consternation amongst some North American cicindelophiles. The argument went something like, “Now we have all these new genus names to learn, and we’ll have to relabel and reorganize everything in our collections, and how do we know the names won’t change again, and we can’t even tell them apart in the field anyway, and blah blah…” Pardon me, but since when did taxonomy become more about slotting species into fixed, easy-to-learn categories and less about best reflecting dynamic knowledge of complex evolutionary relationships? In the case of Cicindela and its former subgenera, however, even these arguments don’t hold up to close scrutiny—tiger beetle enthusiasts in North America should have already been quite familiar with the former subgenera due to their inclusion in the widely accepted Pearson et al. (2006) field guide, many of which actually do present a unique suite of morphological/ecological characters that facilitate their recognition in the field, and I personally find that nomenclatural recognition of individual lineages helps my attempts to learn and understand them much more than dumping them into a large, all-encompassing genus based on superficial resemblance. As for insisting that names don’t change, well that has never been a tenet of taxonomy. Stable, yes, but fixed and immutable, no.

Ellipsoptera marginata male | Pinellas Co., Florida

Enough waxing philosophic. One of the more distinctive of the former subgenera is Ellipsoptera. Morphologically the genus is defined by details of male genitalia, but the 11 North American species are generally recognizable in the field by their relatively “bug-eyed” look and long legs (Pearson et al. 2006) and, as a group, seem ecologically tied to extreme habitats with sandy and/or saline substrates that are nearly or completely devoid of vegetation. Coastal marshes and mudflats, saline flats, sandy river banks, and deep sand ridges representing ancient coastlines are some of the habitats where species in this genus are most commonly encountered. Most of the species exhibit a fairly uniform facies but differ in the details of maculation and dorsal coloration, but two species that stand apart from the rest are E. marginata (Margined Tiger Beetle) and E. hamata (Coastal Tiger Beetle) due to the highly diffuse middle band of their elytra. These are both eastern coastal species and presumably represent sibling species that have diverged based on geographical range partitioning—E. marginata along the Atlantic Coast and E. hamata along the Gulf Coast. In the field, the two species are almost identical in appearance but nonetheless easily identifiable based on geographical occurrence. There is, however, a small stretch of coastline—the lower Gulf Coast of Florida—where the ranges of the two species overlap and geography alone isn’t sufficient for species determination.

Ellipsoptera hamata lacerata male | Dixie Co., Florida

Fortunately, despite their strong resemblance to each other, field identifications in areas where these species co-occur are still possible due to the presence of small but distinct sexual characters present in one species but absent in the other. Close examination is necessary to see the characters (or their absence), so it is best to net a few individuals and examine them in the hand or, as I have done here, look at them through the viewfinder of a camera. The photos in this post include the male and the female of both species, each showing the presence or absence of the distinguishing character.

Ellipsoptera marginata female | Dixie Co., Florida

In most tiger beetles, male individuals are distinguished by a number of secondary sex characters, but easiest to see in the field are the brush-like pads on the underside of the front tarsi (“feet”). Males of E. marginata and E. hamata are further distinguished from each other by the presence (E. marginata) or absence (E. hamata) of a distinct tooth on the underside of the right mandible. Photo 1 above shows a male E. marginata from Pinellas Co., Florida, and the tooth is easily seen in that relatively distant view. Photo 2 above shows a male E. hamata lacerata (Gulf Coast Tiger Beetle)—the Floridian subspecies, and while a small bump can be seen on the underside of the right mandible, it is not nearly as well developed into a distinct tooth as in E. marginata.

Ellipsoptera hamata lacerata female | Dixie Co., Florida

Female tiger beetles, on the other hand, lack the brush-like tarsal pads present in the males and are further distinguished by the “mesopleural coupling sulcus”—an area just behind the side of the pronotum that receives the male mandible during mating and is thus devoid of setae (compare the females in Photos 3 and 4 with the males in Photos 1 and 2). Neither E. marginata nor E. hamata females possess the mandibular tooth found in E. marginata males, but they can be distinguished from each other by their elytral apices. In E. marginata females (Photo 3), the elytra are curiously “bent” at the tips, forming a distinct indentation at the apex of the elytra where they meet, while female E. hamata (Photo 4) lack this indentation.

Are there other tiger beetle sibling species groups for which you would like to see comparative posts such as this one?

p.s. I completely neglected to mark yesterday’s 5th anniversary of Beetles in the Bush! I don’t know how I missed a milestone as big as five years—hopefully my ability to provide interesting content is faring better than my middle-aged memory!

REFERENCES:

Erwin, T. L. and D. L. Pearson. 2008. A Treatise on the Western Hemisphere Caraboidea (Coleoptera). Their classification, distributions, and ways of life. Volume II (Carabidae-Nebriiformes 2-Cicindelitae). Pensoft Series Faunistica 84. Pensoft Publishers, Sofia, 400 pp.

Pearson, D. L., C. B. Knisley and C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press, New York, 227 pp.

Copyright © Ted C. MacRae 2012

The Third of Florida’s Three Metallic Tiger Beetles

/ Ted C. MacRae / 7 Comments

Tetracha virginica (Virginia Metallic Tiger Beetle) | Levy Co., Florida

After three straight posts not about tiger beetles, I’m hoping readers will forgive my return to this fascinating group. The photos in this post represent Tetracha virginica (Virginia Metallic Tiger Beetle), the most widely distributed (at least in the U.S.) of the four species occurring in North America north of Mexico. Even though this species occurs in my home state of Missouri, I’d not found an opportunity to photograph it until August last year at Florida’s “Road to Nowhere“—famous among U.S. cicindelophiles as one of the country’s true tiger beetle “hot spots.” In fact, it was on the very same night at this same place that I photographed the related Tetracha carolina (Carolina Metallic Tiger Beetle) (featured in Not all Florida tiger beetles are rare) and just one day after I photographed the endemic Tetracha floridana (Florida Metallic Tiger Beetle) (featured in Why I Roamed the Marsh at Night). That’s all three species of Tetracha occurring in Florida in just two days (and if I want to photograph the fourth and only remaining U.S. species, Tetracha impressus (Upland Metallic Tiger Beetle), I’ll have to go to Brownsville, Texas and get very lucky!).

The solid green elytra without apical markings distinguish this species from all other Tetracha spp. in the U.S.

Truthfully, I had no plans to post these photos after I took them. Like the other species they were photographed at night, and when I got a better look at the photos on the computer I was disappointed to see the subject was badly covered with large particles of sand. I don’t mind a little bit of debris on insects—it is, after all, a normal part of their appearance. However, too much debris is, for me, an aesthetics killer! “Wait a minute… these don’t look too bad”, you say? Well, thanks to the Clone Stamp Tool in Photoshop Elements, and as a followup to my recent post on this subject, I now have enough confidence to tackle not only small pieces of debris, but also more difficult “debris cases” such as this one with relatively large particles. Here is the same photo as shown above and processed in exactly the same manner, except that no cloning was used to remove the debris:

Aren’t I a dirty boy?!

Obviously, there are limits to what the Clone Stamp Tool can do, and I didn’t try to deal with the sand particles clinging to more difficult to clone body parts such as legs and antennae (although I’m sure that in the right hands even these could be cloned out). Nevertheless, even just cleaning the dorsal surface of the beetle does much to improve its appearance with a relatively minor amount of effort.

And, of course, what would a tiger beetle post be if it did not end with my signature face portrait (notwithstanding a few large sand grains that I wasn’t sure I could clone out effectively)?

Copyright © Ted C. MacRae 2012

Sexual Profiles

/ Ted C. MacRae / 3 Comments

I recently happened upon these photographs of Habroscelimorpha severa (Saltmarsh Tiger Beetle), taken in early August last year at the terminus of Florida’s famous “Road to Nowhere“. I hadn’t thought to post them afterwards because I’d already shown a photograph of this species taken at the same spot during the previous year’s visit. I should have, as they are much better photographs than that initial attempt. Blame part of the first attempt on the fact that I was only in my third month of insect macrophotography, but the biggest reason for the improvement was because I’d gotten a little smarter and learned to use a blacklight to bring these extremely wary beetles to me at night rather than try to chase after them during the day. Still, I don’t get much enjoyment out of posting photos for no other reason than to post photos, so they’ve sat on my hard drive for the past year and a half. In looking at them again, however, I realized that the first and second, profiles of a female and a male, respectively, make for a nice comparison of the secondary sexual characters exhibited by adults of this species.

Habroscelimorpha severa (female) | Levy Co., Florida

Females exhibit fewer sexual characters than males, the main one being the presence of grooves on each side at the back of the pronotum (neck). These grooves function during mating, at which time the male grasps the female by the pronotum with his mandibles. This helps to provide a more secure grip for the male to prevent him from being dislodged during mating and subsequent mate guarding. The grooves themselves are not obvious in the photo, but the lack of setae (hairs) within them is, giving the female a less “hairy” look than the male. As with most insects, females also are more robust—their abdomens larger to make room for egg-making machinery, although in this and other tiger beetle species the difference is not that obvious.

Image

Habroscelimorpha severa (male) | Levy Co., Florida

Males are immediately recognizable by several respects. In addition to the smaller abdomen and “hairier” pronotum lacking lateral grooves, male tiger beetles in most of the “higher” genera exhibit brush-like pads on the undersides of the front tarsi (feet). The function of these pads is not completely clear, but prevailing opinion is that they somehow aid in gripping the female during mating. I’m not sure I buy into this—males do sometimes hold onto females with their front legs during mating, but how these pads improve grip escapes me. Further, it is my experience that males actually spend more time during mating and mate guarding with their front legs outstretched to each side. I’ve also noticed that males are reluctant to release females even when danger approaches (even in the form of a giant insect macrophotographer). I’ve seen males tenaciously clinging to the female as she violently tries to shake him off and flee from my approach. It makes me think that perhaps the tarsal pads serve some tactile function as a final warning of impending danger to a grasping male, allowing him to not give up his female until absolutely necessary (hey, it’s an idea—if you have an alternative idea I’d love to hear it). There is more, however—look at that big head!

Habroscelimorpha severa (male) | Levy Co., Florida

Actually,  the male’s head is no larger than the female’s, but the proportionately longer mandibles give the male a distinctly “big-headed” look.  In contrast, the labrum (upper lip) is shorter than the female’s (making the mandibles look longer still). Both of these characters are, again, related to the habit of grasping the female pronotum, with the longer mandibles allowing a more secure grip of the female pronotum and the shorter labrum adding even more functional length to the mandibles (I can also imagine that this might have some effect on choice of prey by males versus females). The male mandibles also have a greater amount of white coloration at their bases—this might simply be a function of the relatively larger size of the mandibles, but given that males of many species exhibit more white overall on both the mandibles and the labrum (the latter of which is usually smaller), it seems more logical to me that the white coloration serves as a visual cue for potential mate recognition.

“Hey baby, I like your grooves!”

“Yeah, well your white lips aren’t so bad either.”

Copyright © Ted C. MacRae 2012

A black background is better… sometimes

/ Ted C. MacRae / 6 Comments

Eriophora ravilla (a tropical orb weaver) | Pinellas Co., Florida

If there is one subject that causes more disagreement among macrophotographers, it is the pitch black background. Granted, black backgrounds are common—almost ubiquitous in macrophotography, since they are easily created by using full flash illumination and ensuring that nothing lies behind the subject close enough to reflect the light from the flash. Detractors, however, claim that it gives subjects an ‘unnatural’ look, as they are rarely seen this way in nature. This may be true, but I still believe that for some subjects the black background simply cannot be beat for its aesthetics, even if the subject is not normally seen in this manner. Take, for example, the Great Plains ladies’-tresses orchid—nothing but a pitch black background could better showcase the delicate, white blossom and its almost crystalline lower lip!

That said, however, there are some subjects for which a pitch black background actually can be considered a ‘normal’ background. This tropical orb weaver spider (Eriophora ravilla) is one example. Unlike many other members of the family Araneidae (orb weavers), species in this genus are strictly nocturnal and not seen hanging on a web during daylight hours. Hiding in a curled leaf during the day, they emerge at night and build a large web (up to 1 meter wide), only to consume it by morning and return to their hiding place until the next evening. My nephew Jack and daughter Madison and I first saw this spider during our nighttime foray into the intertidal mangrove marsh behind my sister-in-law’s condominium in Seminole, Florida last month while discovering rare, endemic beetles and their larvae. Knowing that it would likely build its web in the same place on subsequent evenings, I went out a few nights later with my camera and took a few shots.

Some claim that black backgrounds are undesirable for even nocturnal subjects; that there is nothing ‘natural’ about an artificial, narrow beam of light illuminating a single subject at night since no animal other than a person with a flashlight would see something like this. This contention seems a little strained, as one could take such a stance on illumination of any kind. Technically speaking even colors don’t actually exist, so the rendering of subject images on camera film/sensor, whether by natural or artificial illumination,  is itself biased towards human sensibilities. Regardless, the sight of an eerily glowing spider hanging in the blackness strikes a familiar chord with anyone who has wandered the bush by night. A black background not only recreates that human experience, but also emphasizes the subject’s (in this case strictly) nocturnal nature with stark elegance.

At first I took this spider to represent the very common barn spider, Neosona crucifera—widespread across North America. However, after noting the dark femora and yellow “shoulders” of the abdomen I began to rethink that ID. Fortunately, I took one photo of the ventral side (not shown) that shows well the color pattern diagnostic for the circum-Caribbean species E. ravilla.

Copyright © Ted C. MacRae

Even a 12-year old can discover the larva of a rare, endemic species!

/ Ted C. MacRae / 13 Comments

Since discovering the larva of the rare, endemic Florida metallic tiger beetle (Tetracha floridana) in the small, intertidal mangrove marsh behind my sister-in-law’s condominium in Seminole, Florida three years ago, I’ve looked forward to subsequent visits to see the adults (they’re nocturnal) and gather additional material needed to write the larval description. I had to wait a few days on this year’s trip due to rain (it is Florida, after all), but eventually a dry evening came along and I began “suiting up” for my nighttime foray. Much to my delight, my 12-year old nephew Jack wanted to come with me. Jack had never been in the field with me before, but according to his mom he has become quite interested of late in science and biology. My daughter Maddie, also 12 years old (and a veteran of many trips to the field with me), also wanted to go, so together the three of us slathered on the insect repellent and headed into the dark towards the marsh.

Larva of Micronaspis floridana (Florida intertidal firefly) | Pinellas Co., Florida

We had only my headlamp as a light source, so the kids trailed behind me as I picked a line through the brush, across a small creek, and onto a ridge that snakes through the marsh that marked one of the areas where I had seen good numbers of the beetles last year. We collected a small number to keep alive and place in a terrarium of native soil, the hope being that they would lay eggs so I could obtain some 1st-instar larvae for the formal description, but what I was really looking for were larval burrows. As we (well, I) searched the ground in front of me with the lamp and the kids trailed behind me in the dark, Jack suddenly stopped and said, “What’s that?” I shone my light to where he was pointing but didn’t see anything and so resumed my search. Right away he said, “There it is again.” I asked if it was a rabbit (we’d seen them at the edge of the marsh during the day), and he said, “No, it’s like a light or something.” I turned off the lamp, and gradually the faint, green glow reappeared. I recognized the source of the light instantly as that of a larval firefly, although truthfully I have never actually seen an actual firefly larva. Seeing a great teaching moment for the kids, we walked to the light, knelt down, and shone the lamp directly on the ground from where the light was coming to find the small (~10 mm long) larva moving slowly through the moist, algae-covered rocks. It had the classic, retractable firefly head and curiously quadruply-spined tergites. I congratulated Jack on finding the larva, emphasizing that I would have never seen it myself had he not been there and been so observant despite not having a lamp.

Larvae of this species exhibit the retractable head characteristic of firefly larvae.

I went back a few nights later by myself so I could concentrate on photographing some of the things we saw in the marsh the previous night, including the firefly larva. I had no problem relocating one in the same place we found it before (I just turned off my headlamp and waited for the green glow). I’m generally not keen on posting photographs of unidentified insects (just me, but I find photos much more interesting when accompanied by the natural history back story), and I was sure this larva would remain unidentified (I have little knowledge of adult fireflies, much less their larvae). This seemed even more likely after perusing the few identified and many unidentified firefly larvae photographs on BugGuide and finding nothing even remotely similar. I was about to give up when I decided to try the search term “Lampyridae Florida Pinellas” (“Pinellas” being the county where we found the larvae—my thinking being that maybe there was a Florida firefly checklist that could narrow down to the county level the possible species), and high in the results was a page titled Florida intertidal firefly (fiddler crab firefly). On that page was a photo of the larva, although not nearly large and detailed enough to be sure it was the same, but still in my mind almost surely this species because of the stated restricted habitat—intertidal zone of Florida coastal salt marshes! I sent these photographs to lampyroid aficionado Joe Cicero, who kindly confirmed my identification. 

Restricted to intertidal marshes in coastal Florida.

Because it occurs only at the edges of salt water marshes around the peninsular coast of Florida, M. floridana is a classic example of shoestring geographic isolation and, thus, serves as a good model for studies of genetic isolation and its impact on speciation (Lloyd 2001). Along with T. floridana, it now makes at least two rare, Florida-endemics occurring in the small private, preserve behind my sister-in-law’s condominium (both of which were first found as larvae rather than adults). Although the larva of M. floridana is already known—albeit by a rough black and white photograph (McDermott 1954)—it’s rarity and restricted habitat nonetheless make it an exciting find well deserving of the more detailed color photographs shown here. However, as I told Jack after receiving confirmation of its identity, he gets full credit for the discovery. I took him into the field with me with the intention of showing him some new things, and he turned the tables on me! Yes, even a 12-year old can discover the larva of a rare, endemic species!

REFERENCES:

Lloyd, J. E. 2001. On research and entomological education V: a species concept for fireflyers, at the bench and in old fields, and back to the Wisconsian Glacier. Florida Entomologist 84(4):587–601.

McDermott, F. A. 1954. The larva of Micronaspis floridana Green. The Coleopterists Bulletin 8(3/4):59–62.

Copyright © Ted C. MacRae 2012