Predator or Prey?

Ellipsoptera hamata lacerata | Dixie Co., Florida

Everyone knows that tiger beetles are predators, but look closely at the underside of the head of this female Ellipsoptera hamata lacerata (Gulf Beach Tiger Beetle), photographed in a coastal marsh in Dixie Co., Florida earlier this month.  See the ant head attached by its mandibles to the base of the tiger beetle’s left maxillary palpus?  Detached ant heads latched onto the palp or antenna of a tiger beetle are a fairly common sight—Pearson and Vogler (2001) show the head of an ant attached to the antenna of Eunota togata (Cloaked Tiger Beetle), and Pearson et al. (2006) show one attached to the antennae of Cicindela formosa (Big Sand Tiger Beetle).  I’ve also photographed Cylindera celeripes (Swift Tiger Beetle) with an ant head attached to its antenna.  Pearson and Vogler (2001) and Pearson et al. (2006) both suggest that the ant heads are the result of predation attempts by groups of ants attempting to overpower and kill the tiger beetle, making the ants the predators and the tiger beetles the prey.

Note ant head attached by its mandibles to the base of the tiger beetle's left maxillary palpus.

Although some ants are well known for their predatory horde behavior, I’m not sure I buy this as an explanation for the common occurrence of ant heads attached to tiger beetles.  Tiger beetles themselves often prey on ants, and while I have seen numerous tiger beetles with ant heads attached to them, I have never seen one actually being overpowered by ants (scavenging an already dead tiger beetle, yes—but not overpowering and killing one).  Moreover, the ant heads are nearly always attached to the base of an antenna or palpus—right next to the tiger beetle’s mouth, and almost never on more distal parts of the antennae or other parts of the body.  If the ants were attempting to prey on the tiger beetle, wouldn’t they also (if not even more commonly) be found attached to the tiger beetle’s legs or soft intersegmental membranes?  And how would the ants have come to be decapitated while in the act of attempting to overpower the beetle?  I suggest it is more likely that the ants were prey, latching onto the nearest part of their killer’s body in a last ditch attempt to avoid their inevitable fate.  The antennal and palpal base are about the only tiger beetle body parts that would be within reach of an ant in a tiger beetle’s toothy grasp.  While the rest of the ant was consumed, the head remained because it was firmly attached to the beetle.

I realize that an identification based only on the detached head of an ant may be difficult, but if one is possible it would be appreciated.  The ant head shown in Pearson and Vogler (2001) was identified as Polyergus sp.

REFERENCES:

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.

Pearson, D. L. and A. P. Vogler.  2001. Tiger Beetles: The Evolution, Ecology, and Diversity of the Cicindelids.  Cornell University Press, Ithaca, New York, 333 pp.

Copyright © Ted C. MacRae 2011

Photographing the Newly Rediscovered Cicindelidia floridana

Cicindelidia floridana | Richmond Heights area, Miami-Dade Co., Florida

When Brzoska et al. (2011) announced the rediscovery of Cicindelidia floridana last April (and also provided convincing evidence for considering it a full species), I could hardly contain my excitement. At a time when increasing numbers of species are being reported in decline or going extinct, the news that this small jewel of a beetle had somehow managed to survive in tiny chunks of remnant habitat (completely surrounded by the sprawling metropolis of Miami) after having not been seen for more than half a century and presumed extinct (Pearson et al. 2006) was cause for celebration.  For me, the timing couldn’t have been better as I was already planning a visit to Florida later in the summer to spend a little time with my family and—of course—search for some of Florida’s several endemic tiger beetle species.  The precise locations where C. floridana have been found have not been publicly disclosed (for obvious reasons), but when I contacted lead author Dave Brzoska and told him of my plans to be in Florida this summer and my interest in seeing the beetles, he graciously offered to take me to the sites himself.  Expedition turned to party when Chris Wirth, author of the cicindelocentric blog Cicindela, made arrangements to fly down from Virginia and join Dave and I on our trip.  This would be Chris’ second visit to see the beetles, having been one of the very lucky first few to see it after its rediscovery while assisting second author Barry Knisley on the initial surveys that were conducted.  For me, it was a cicindelophile’s dream come true—a day in the field with Dave (whom I had not seen in more than 25 years), meeting Chris for the first time, and looking for and (hopefully) photographing one of North America’s rarest tiger beetles.

Pine rockland habitat for Cicindelidia floridana.

Adults beetles frequent sparsely vegetated sandy exposures in the palmetto understory.

After a delightful evening looking at meticulously curated specimens in Dave’s astounding collection, the three of us left early the following morning from his home in Naples to make the 2½-hr drive to Miami.  Temperatures in south Florida during early August can soar as the day progresses, and as they do the beetles—already flighty and difficult to observe—become even more so before eventually taking refuge under debris.  We arrived at the first site right at mid-morning, at which time I was allowed to remove my blindfold (just kidding!).  One of the features that distinguishes this species from C. scabrosa is its habitat—south Florida pine rockland as opposed to the more widespread peninsular sand pine scrub habitat frequented by C. scabrosaPine rockland is a fire-adapted community composed of an open canopy of south Florida slash pine (Pinus elliottii var. densa) and a diverse understory of cabbage palm (Sabal palmetto) and other shrubs.  As I readied my camera gear, Dave told me to look for small exposures in the understory and then watch them for any sign of movement.  The adult beetles, despite their brilliant coloration, are among the smallest tiger beetle species and are exceedingly difficult to detect amongst the vegetation and debris covering the soil.  I could have just let Dave look for the beetle first while I tagged along and then let him “show” them to me, but I wanted to find them for myself, so I struck out on my own and started searching.

Shiny green coloration and reduced elytral maculation distinguish this species from C. scabrosa.

It wasn’t long before I heard Dave and Chris call out that they had seen one, and while the temptation was great to go over to where they were and look at what they had already found, I stayed the course and continued searching on my own.  Finally, I saw one!  It was gorgeous and brilliantly colored—much more copperish in appearance than I had expected (Dave later explained that this is something seen better in the live beetles and not so well in preserved specimens).  Deciding how to approach an unfamiliar tiger beetle for photography is always a crap shoot—until one gets a feel for its behavior and the way it reacts to movement it is difficult to know precisely how to approach it.  I had gone ahead and tempted fate by mounting my 65mm macro lens and its very short working distance, so I would need to draw on the entirely of my experience in photographing tiger beetles to figure out how to get close enough to these beetles to photograph them.  I hadn’t even gotten down on my knees yet before the first adult took flight and disappeared before my eyes.  Knowing what to look for now, I continued searching and found another adult after a short time—with the same result!  Beetle after beetle appeared before me on the sparsely vegetated sand openings and then zipped away well before I had the camera in position.  Finally, by about the 10th beetle that I saw I found one that seemed a little more cooperative (or maybe I had just finally learned how to move in on them).  I carefully, slowly layed down on the ground and got the camera in position as the beetle skitted here and there, obliviously feeding on the occasional ant, then located it in the viewfinder and started firing off shot after shot.  The two photos above represent my favorites from that series and well show not only the elytral sculpturing and flattened pronotal setae that distinguish both this species and C. scabrosa from the other members of the group (C. abdominalis and C. highlandensis), but also the bright greenish coloration, reduced elytral maculation, and lighter leg coloration that Brzoska et al. (2011) used as justification for elevation to a full species distinct from C. scabrosa.

Cicindelidia floridana adults mating.

After failing to get more shots of the next 10 or so adults that I found, I saw a male hop on top of a female and attempt to mate.  I quickly got into position to photograph them, but just as I got them framed they uncoupled and ran their separate ways.  I figured I had probably lost my only chance to photograph a mating pair, but shortly afterwards I encountered another couple that was already engaged.  I saw them before they became disturbed and moved, and as a result I found it relatively (relatively!) easy to get in position and begin photographing without alarming them.  Tiger beetles are often encountered coupled but not actively mating, as the males will often ‘mate guard’ a female for an extended period after mating to prevent other males from mating with her (in many beetles, the last male to mate with a female stands a greater chance of fertizilizing the eggs she lays) (Pearson and Vogler 2001).  This couple, however, was actively engaged as evidenced by the exserted male genitalia firmly penetrating the female genital opening.

Genitalia actively engaged.

I watched the mating pair for a period of time and notice that at times the male held the female more tightly with his front legs, while at other times he held his front legs extended widely out to the sides.  I have seen this same behavior in nearly every tiger beetle species in which I have observed mating pairs and have yet to find or intuit an explanation.  The male has dense, brush-like pads on the undersides of the front tarsi, which presumably are used to aid in grasping the female during mating and may also possibly aid in signaling during courtship.  Perhaps extending the legs to the sides is done at times when the female is not struggling to dislodge the male (itself an interesting subject), allowing them to serve a tactile function to better warn against intruding males.

Sometimes the male held his forelegs against the female...

...while other times the forelegs were extended widely to the sides.

All told we spent about 2½ hours at the site, and I estimate that I saw a total of approximately 30 beetles.  Some may have been the same as those I had seen before, since I tended to focus my searches in three small areas of sandy exposures not too distant from each other.  Chris and Dave each worked separate areas as well, also seeing a good number of beetles and suggesting that the population at this site, despite the limited extent, is quite good.  Puddles of water on the road as we entered the site indicated that the site had received recent rains, which may have been at least partly responsible for the level of adult activity observed. We drove by additional pine rockland remnants in the vicinity before heading back to Naples, some of which are known to contain the beetle and others that still need additional survey to determine the presence of the beetle and its status. With an extent of suitable habitat that is among the smallest of all North American tiger beetles, I suspect that C. floridana will be a good candidate for listing on the Endangered Species List. It will be a second chance for the beetle—and for us to see if we will be able to muster the will to save a species once thought extinct from actually becoming so.

Me with Dave "Dr. Tiger Beetle" Brzoska.

Tiger beetle photographer extraordinaire Chris Wirth.

Congratulations to Ben Coulter, who returns to his winning form and takes this first round in the current BitB Challenge Session (#4) with 14 points. Dave Hubble takes 2nd with 12 points, while Mr. Phidippus and FlaPak tie for the final podium spot with 10 points each.  Nine other participants tested their skills, and if you didn’t play, they’ve all now got the jump on you!

REFERENCES:

Brzoska, D., C. B. Knisley, and J. Slotten.  2011.  Rediscovery of Cicindela scabrosa floridana Cartwright (Coleoptera: Cicindelidae) and its elevation to species level. Insecta Mundi 0162:1–7.

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.

Pearson, D. L. and A. P. Vogler. 2001. Tiger Beetles: The Evolution, Ecology, and Diversity of the Cicindelids.  Cornell University Press, Ithaca, N.Y., xiii + 333 pp.

Copyright © Ted C. MacRae 2011

ID Challenge #10

It’s time to begin Session #4 of the BitB Challenge Series.  Ben Coulter won Sessions #1 and #2 but was finally unseated by Max Barclay in Session #3.  We start Session #4 with a straight up ID Challenge.  Unlike previous ID Challenges, however, the order and family are gimmes this time, so I’m going to take them off the table and award double (4) points each for the correct genus and species (suggestion: being a stickler for details will increase your chances for full points).  Standard challenge rules apply, including moderated comments (to give everyone a chance to take part) and possible bonus points for being the first to guess correctly (if multiple people offer the same correct answers), offering additional relevant information, or—as always—the ability to make me chuckle.

Reminder: nobody walks away empty-handed, so it pays to try even if you think you’re stumped.  The pity points you earn in IDC#10 could make a difference in the final standings at the end of Session #4.

Good luck!


Copyright © Ted C. MacRae 2011

Tiger Beetle Nocturnal Perching

Ellipsoptera hamata lacerata | "Road to Nowhere" Dixie Co., Florida

During last week’s 48-hour blitz through Florida, I spent one evening blacklighting at the famed “Road to Nowhere” tiger beetle hot spot and encountered this male individual of Ellipsoptera hamata lacerata¹ clinging to the grass near my light.  A quick search of the surrounding area revealed a number of similarly perched individuals, including a mating pair and all representing the same species.

¹ Males (identified by the brushy pads under the foretarsi) of this species are distinguished from the closely related E. marginata, which co-occurs with E. hamata lacerata along the Gulf coast of Florida, by the lack of a distinct tooth on the underside of the right mandible.

Like many species in this and related tiger beetle genera, E. hamata is diurnal but also highly attracted to lights at night. This is thought to be related to nocturnal dispersion behaviors (Pearson and Vogler 2001) intended to avoid higher daytime predation risks. Nocturnal perching on foliage is also common among diurnally-active species in riparian habitats and seems also to be an adaptation for reducing predation. Pearson and Anderson (1985) noted that perched beetles removed from the grass and placed on the ground were often quickly preyed upon by larger nocturnally-active tiger beetles. At “Road to Nowhere” this might include the slightly larger Habroscelimorpha severa which occurred in enormous numbers alongside this species on the mud flats, or the much larger Tetracha virginica which occurred in fair numbers on the adjacent road.

REFERENCES:

Pearson, D. L. and J. J. Anderson.  1985. Perching heights and nocturnal communal roosts of some tiger beetles (Coleoptera: Cicindelidae) in southeastern Peru.  Biotropica 17(2):126–129.

Pearson, D. L. and A. P. Vogler. 2001. Tiger Beetles: The Evolution, Ecology, and Diversity of the Cicindelids.  Cornell University Press, Ithaca, N.Y., xiii + 333 pp.

Copyright © Ted C. MacRae 2011

Charming Couple

You may have noticed a longer than normal interval since the last post (or not)—the result of a family vacation to Florida.  I’m not much of a beach bum, so while the girls found inordinate pleasure laying on the hot sand and doing absolutely nothing while being baked to a crisp by the almost tropical Florida sun, I took the opportunity to look for some of Florida’s gorgeous and often endemic tiger beetles.  I visited a diversity of habitats to both the north and south of my base near St. Petersburg ranging from white sand beach to salt marsh to oak/pine sand scrub to pine rockland.  I photographed tiger beetles both at night and during the day (laying on the hot sand while being baked to a crisp by the almost tropical Florida sun!).  In total I encountered eleven tiger beetle species—five of them true Florida endemics.  We’re on our way back now, and photos are just now getting downloaded and processed, so I’m not quite ready yet to begin sharing stories in earnest.  Until then, here is a photograph of a mating pair of one of Florida’s classic coastal tiger beetle species, Ellipsoptera hamata lacerata (Gulf Beach Tiger Beetle).

Ellipsoptera hamata lacerata (Gulf Beach Tiger Beetle) | Seminole, Florida

Photo Details: Canon 50D (ISO 160, 1/200 sec, f/16) w/ 100mm macro lens + Kenko DG extension tubes (68 mm), Canon MT-24EX flash w/ DIY oversized concave diffuser. Post-processing to adjust levels and apply unsharp mask.

Copyright © Ted C. MacRae 2011

Cylindera cursitans (Ant-like Tiger Beetle) in Arkansas

In late June I visited Chalk Bluff Natural Area in northeastern Arkansas.  Situated at the northeastern-most corner of the state, it is here where the St. Francis River enters Arkansas from Missouri, slicing through the loose Tertiary conglomerates of Crowley’s Ridge before settling into its lazy, meandering course between the two states in the Upper Mississippi Alluvial Plain.  The site’s geological history, however, is not what attracted me to it, but rather its status as the state’s only known locality for Cylindera cursitans (ant-like tiger beetle).  It was the existence of this population that convinced my colleagues Chris Brown and Kent Fothergill and I that the species must occur in southeast Missouri not only along the Mississippi River, but also along the St. Francis River some 50 miles to the west.  Persistence eventually paid off last year when Kent captured a single individual on the Missouri side of the river at Chalk Bluff Access in Dunklin Co. (MacRae et al. 2011).

Kent had to really work for that specimen, spending several hours crawling through the underbrush in wet, bottomland forests before eventually finding the lone individual.  I was confident, however, that my search at the Arkansas site would require far less effort, as Kent had also observed this population during his attempts to locate the species on the Missouri side of the river, writing “I saw more cursitans in an hour than I have seen lifetime total!” The playground/picnic area where Kent had seen them sits right next to the parking lot and is as un-curitans a habitat as one can imagine—tidy and neat, with a nicely-mowed grass lawn under the shade of large oak trees rather than the sweltering, poison ivy choked understory habitats with their attendant swarms of mosquitoes and deer flies that we’ve braved in order to find the species in Missouri.  Only the small, intermittent patches of barren sandy loam soil gave a clue that this might be good tiger beetle habitat, and even then one might expect only the more pedestrian species such as Cicindela punctulata and Tetracha virginica and not something as exciting as C. cursitans.

But occur there it does, and hardly a few steps had been taken from the parking lot before I saw that familiar “dash” of movement, looking for all intents and purposes at first like a small spider.  A closer look confirmed its true identity, and during the next hour or so I would see countless such individuals—all scrambling rapidly for cover on my approach.  I have seen a number of cursitans populations during the course of our surveys for this species in southeastern Missouri, and this population was as robust as any of them.

Despite my earlier work with this species, I still lacked photographs I was completely happy with—i.e., field photographs of unconfined beetles taken with a true macro lens and flash to control lighting.  All of my previous photographs were either taken with a small point-and-shoot camera or had to rely upon beetles confined in a terrarium.  The species is not easy to photograph in the field—the small size of the adults (6–8 mm in length) and their cryptic coloration matching the soil surface makes them almost impossible to see until they move.  They are also very skittish and are quick to flee when approached, necessitating very slow, deliberate movements in order to approach them closely enough for photographs.  Oftentimes adults will run towards and hide up against the base of a clump of grass, where they are even more difficult to photograph, but sometimes they will hide beneath fallen leaves or other debris.  Interestingly they do not flee immediately if the leaf/debris is very carefully lifted up and removed—almost as if they think they’re still hidden.  I’ve found exposing adults hiding under leaves to be an easier way to get field photographs of the species, although I have noted that some individuals (but not others) seem eventually to adjust to my presence and resume normal activity despite having a camera lens hovering inches away from them.

Once I had my fill of photographs, I walked the trail to the river and back but did not see any beetles along the trail within the forest (too much leaf litter) or along the river.  Surely the beetles occur in these other areas and are not confined in the area just to that small, man-made habitat that is the picnic ground.  Seeing this population gives me greater confidence that the species does indeed occur more broadly along the St. Francis River in Missouri than suggested by single individual caught on the Missouri side by Kent.

REFERENCE:

MacRae, T. C., C. R. Brown and K. Fothergill. 2011. Distribution, seasonal occurrence and conservation status of Cylindera (s. str.) cursitans (LeConte) (Coleoptera: Carabidae: Cicindelitae) in Missouri. Cicindela 43(3): in press.

Copyright © Ted C. MacRae 2011