Tiger Beetles at Florida’s “Road to Nowhere”

(continued from the previous post, Tiger Beetles Agree—It’s Hot in Florida!)

During the time that I explored the pine sandhill habitat at Withlacoochee State Forest in Citrus County, I kept close watch for any individuals amongst the dozens and dozens of Cicindela abdominalis (Eastern Pinebarrens Tiger Beetle) that I encountered that might exhibit the deeply pitted rather than smooth elytral surface that would identify it as the closely related Florida-endemic, Cicindela scabrosa (Scabrous Tiger Beetle).  However, no such individuals would be seen (my first tiger beetle failure of the trip), and having already spent more than two hours at the site I decided it was time to move on the the “Road to Nowhere.”

"Road to Nowhere," 11.1 mi S Jena on Hwy 361, Dixie Co., Florida

The Road to Nowhere is a tidal marsh (also known as “coastal salt marsh”) near Steinhatchee in Dixie County (11.1 mi S Jena on Hwy 361).  Although I was not aware of it prior to my August visit, this locality has achieved legendary status among tiger beetle enthusiasts because of the great number of species that can be seen there—as many as 6–10 species in the right season.  Being a coastal wetland with moist, saline substrates, these would include such species as Cicindela trifasciata ascendens (Ascendent Tiger Beetle), Habroscelimorpha severa (Saltmarsh Tiger Beetle), the rarely collected H. striga (Elusive Tiger Beetle), and Eunota togata togata (White-cloaked Tiger Beetle), in addition to Ellipsoptera marginata (Margined Tiger Beetle) and E. hamata lacerata (Gulf Beach Tiger Beetle) which I had already found a few days earlier.  As I found the highway leading to the spot and begain to drive its upper reaches, I looked longingly at the barren sand exposures along the sides of the road thinking that C. scabrosa, already known from the area (Choate 2003) must be there.  However, it was well into the afternoon hours by then, and having already failed to find the species at Withlacoochee State Forest, I decided I should press on and see what the Road to Nowhere had to offer.

Cicindela (Cicindelidia) trifasciata ascendens—Ascendent Tiger Beetle

Almost immediately I began seeing tiger beetles.  The first species I saw was C. trifasciata ascendens—rather common on areas of the flats close to the water’s edge.  I recognized them instantly, as I had not only seen this species some years ago in south Texas, but also in southern Missouri as a lone vagrant (Brown and MacRae 2005).  The dark brown dorsal coloration and thin, sinuous, S-shaped middle maculation are diagnostic for the species (Pearson et al. 2006).  While it was by now late afternoon, the heat of the day had not yet begun to subside, and the beetles were extremely active and flighty.  The difficulty in approaching them closely enough for photographs was exacerbated by the wet, muddy substrate and incessant drone of tenacious mosquitoes intent on breaching my invisible shield of DEET.  Eventually, however, and only due to one decidedly more cooperative individual (above), I succeeded in getting a few shots with which I was happy. 

Habroscelimorpha severa—Saltmarsh Tiger Beetle

Far less common than C. trifasciata ascendens, but equally skittish, was the impressive H. severa.  I have also seen this species before in south Texas, though not in great numbers, and its shiny green surface with maculations reduced to small spots at the middle and rear of the elytra are unmistakealbe.  It was the hardest to approach of the species I saw, and the above (only slightly cropped) photograph is as close as I was able to get (it is also the only photograph from the field session that was good enough and close enough to keep).  This species tends to be most active in the morning and again in the evening, so most of my late-day efforts focused on this species—in fact, it was almost too dark to see by the time I finally quit my attempts at photographing the species.  I brought back one live individual and took some “studio” photographs after I returned home, but I’m still not any happier with them than this lone field shot.

Ellipsoptera hamata lacerata—Gulf Beach Tiger Beetle (reduced maculations)

When I first saw the species represented by the individual in the above photograph, I had not a clue as to its identity—the dark elytra with only a marginal band was unlike anything I would have expected to see.  Quickly thumbing through my “bible” (Pearson et al. 2006), I kept stopping at the plate containing Cicindela marginipennis (Cobblestone Tiger Beetle).  I knew this was impossible, as that species is restricted to several disjunct cobblestone habitats further north.  I collected the specimen for a voucher, keeping it alive for studio photographs, but it wasn’t long before I saw another similar-looking individual.  I decided I must be overlooking something, so after getting photographs and collecting the specimen for another voucher I went back through Pearson.  This time I focused only on the species that could possibly occur here, and realized that it was simply E. hamata lacerata with its normally diffuse middle elytral maculations highly reduced (traces of the middle band can be seen in the photograph).

Ellipsoptera marginata—Margined Tiger Beetle

Ellipsoptera marginata was the most abundant species at this location, and on this day I succeeded in getting a nice photograph of a female with her distinctively downbent elytral apices (see closeup photograph in this post).  This species is very similar to E. hamata, with which it co-occurs along the Gulf Coast of peninsular Florida, but can be immediately recognized by the bent elytral apices (female) or distinct tooth on the underside of the right mandible (male).  Both of these species are distinguished from all other species in the genus by the diffuse middle maculation of the elytra. 

At least two additional species occur at this site, one of which (E. togata) I saw but a single individual of and was unable to photograph, and the other (H. striga) which I did not see.  In fact, the Road to Nowhere is apparently “the” spot for finding the latter species, which occurs predominantly at night and is seen primarily by its attraction to ultraviolet lights.  While I would have liked to stay after dark and setup lights to see this species, I had neither the time nor the equipment to do this.  It may, after all, have been too late in the season anyway—since my visit I’ve heard stories from other tiger beetle aficionados who say the whole area can be filled with collectors from all over the country with their blacklights and bucket traps and someone yelling “striga!” every hour or so.  No such scene developed during my visit, so I suspect my visit was on the late side of the season and that the 5 species I did see represents a pretty good day regardless.  The long drive back to St. Petersburg marked the end of my tiger beetle exploits in Florida, at least for this year.

For another tiger beetling experience at Road to Nowhere, read this post by Doug Taron, who visited the site even later in the season (October).  Although he didn’t see as many tiger beetles, he does provide some interesting details regarding the shady origins of this place.

Photo Details: Canon EOS 50D, ISO 100, 1/250 sec.
Habitat: Canon 17-85mm zoom lens (landscape, 66mm), f/9, natural light.
Insects (except E. marginata): Canon 100mm macro lens (manual), f/22–25, MT-24EX flash w/ Sto-Fen diffusers.
E. marginata: Canon MP-E 65mm 1–5X macro lens (manual), f/16, MT-24EX flash w/ Sto-Fen diffusers.

REFERENCES:

Brown, C. R. and T. C. MacRae. 2005.  Occurrence of Cicindela (Cicindelidia) trifasciata ascendens (Coleoptera: Cicindelidae) in Missouri. Cicindela 37(1–2):17–19.

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.

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 2009

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Florida Metallic Tiger Beetle

Tetracha floridana

Tetracha floridana (Florida Metallic Tiger Beetle), dorsal view

In my previous post, I showed some photographs of the larva of an undetermined species of tiger beetle that I collected from its burrow in dry ground adjacent to a coastal salt marsh near St. Petersburg, Florida. I had assumed the larva belonged to the genus Cicindela or one of its former subgenera and was suprised to learn that this assumption was incorrect when the adult emerged 2 months later. Looking back at the photos, however, I realized that the photos and the information I gave regarding its location and habitat contained all of the necessary information to identify this larva. Five points to Mike Baker, who correctly deduced the genus (Tetracha), and in fact the larva represents Tetracha floridana (Florida metallic tiger beetle).

Hump of 5th abdominal segment, showing simple, thorn-like inner and outer hooks

The hump of the 5th abdominal segment bears simple, thornlike hooks.

The larva can be placed in the genus Tetracha by virtue of its simple, thorn-like hooks (in other eastern U.S. tiger beetle genera, the outer hooks are distinctly curved).  Two other genera of Nearctic tiger beetles that do not occur in Florida also bear simple hooks—Omus (Night-stalking Tiger Beetles, occurring along the Pacific Coast) and Amblychelia (Giant Tiger Beetles, occurring in the central and southwestern U.S.); however, the former bears three rather than two pairs of hooks, and the latter has the inner and outer hooks distinctly separated from each other.

Tetracha_floridana_1

Tetracha floridana (Florida Metallic Tiger Beetle), lateral view.

Four species of Tetracha occur in the U.S., three of which occur in Florida—T. carolina (Pan-American Big-headed Tiger Beetle), T. floridana (Florida Metallic Tiger Beetle), and T. virginica (Virginia Big-headed Tiger Beetle).  However, T. carolina is restricted in the state to the panhandle and interior of the peninsula along rivers and in disturbed sparsely vegetated areas (Choate 2006).  Of the two remaining species, T. virginica is widespread throughout the southern two-thirds of the eastern U.S. and occurs in a variety of habitats (Pearson et al. 2006), while T. floridana is restricted to salt marsh and mud flat habitats along the Gulf coast of Florida from Dixie County south to the Keys (Choate 2006).  While the widespread occurrence and generalist tendencies of T. virginica might suggest that it is the more likely choice, the locality and habitat match precisely with T. floridana.

Tetracha_floridana_2

The anterior lobes of the apical lunules are divergent.

Tetracha floridana is very similar to T. carolina and was long considered a subspecies of that more widely distributed species until Naviaux (2007) elevated it to species rank in his revision of this large genus.  Tetracha floridana is distinguished from T. carolina by the divergent anterior lobes of the apical lunules (photo above) and the uniformly black to dark green elytra that lack any violet or coppery reflections in the anteriolateral regions (photo below) (Choate 2003).

The anteriolateral areas of the elytra lack violet or copper reflections

The anteriolateral areas of the elytra lack violet or copper reflections.

I was happy as heck when I saw the first newly emerged adult in the rearing container, as this is a true Florida endemic.  I have encountered the two other eastern U.S. species commonly under street lamps and at building lights here in Missouri—T. virginica throughout the state and T. carolina in the southeastern lowlands, where it appears to reach its northern limit of distribution.  A fourth U.S. species in the genus, T. impressa (Upland Metallic Tiger Beetle) (T. affinis” in earlier works), occurs in northern Mexico and the Lower Rio Grande Valley (LRGV) of south Texas (Erwin and Pearson 2008).  Although I have not yet encountered it on any of my many trips to the LRGV (all of which pre-date my current cicindelophily), I understand it is regularly attracted to building and street lights in Brownsville (Pearson et al. 2006).  I believe I will have to go down there again and verify this for myself someday.

Feasting on a corn rootworm larva.

Feasting on a corn rootworm larva.

The last photo in this series illustrates the unique feeding behavior of these beetles, which despite their terrifyingly toothy mandibles are strictly fluid feeders.  The long, sharp mandibular teeth function primarily in prey subdual and in slicing and shredding their tissues, while the maxillae (second pair of feeding appendages behind the mandibles) and labium (fused third pair of appendages) comprise an “oral mill” that masticates the prey and and rolls it into a bolus.  Two brush-like structures can be seen behind the mandibles in the photo above—these are part of the maxillary laciniae and apparently function in containing and shaping the bolus as it is being masticated.  While this occurs, proteolytic enzymes are extruded from the midgut and mixed with the bolus to liquify its digestible components, which are then sucked into the beetles tiny mouth by the action of a pharyngeal pump.  Like the larva, the adult beetle thus “chews” but does not swallow its prey—a manner of feeding that is not too unlike that of spiders and other arachnids (sans the venom).

Photo details:
All photos: Canon EOS 50D, manual mode, ISO-100, 1/250 sec, MT-24EX flash w/ diffuser caps.
Photo 1: Canon 100mm macro lens w/ 68mm extension tube, f/25, 1/2 power flash.
Photo 2: Canon MP-E 65mm 1–5X macro lens, f/16, 1/8 power flash.
Photos 3–5: Canon 100mm macro lens w/ 36mm extension, f/18–f/22, 1/4 power flash.
Photo 6: Canon 100mm macro lens w/ 68mm extension, f/20, 1/2 power flash.

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.

Choate, P. M., Jr.  2006.  Tiger Beetles of Florida, Cicindela spp., Megacephala spp. (Insecta: Coleoptera: Cicindelidae).  University of Florida, IFAS Extension Service Circular EENY-005, 5 pp.

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.

Naviaux R. 2007. Tetracha (Coleoptera, Cicindelidae, Megacephalina): Revision du genre et descriptions de nouveaus taxons. Mémoires de la Société entomologique de France 7:1-197.

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 2009

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