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.
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.
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.
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!
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