It’s been too long since I’ve done a good old-fashioned anting expedition. So I took a break on Wednesday to see a part of Illinois rumored to be profoundly different from the rest of the state: Sand Ridge State Forest, a quiet patch of public land southwest of Peoria.
The unique character of Sand Ridge stems from its geologic history. The glaciers ended here, dumping a pile of sand atop the resident clay. The soils here are dry and well drained, a stark contrast to the surrounding tallgrass prairie. As Sand Ridge is too nutrient poor to farm, the land was preserved as a blend of shortgrass sand prairie and woodland. Continue reading →
While I am flattered that many of you use my photo galleries to identify mystery ants, please be aware my site has limitations as a diagnostic tool. In particular, I am missing a lot of species, even some common ones, and even in North America.
Thus, when browsing my galleries looking for a match, bear in mind there’s more diversity than what I’ve posted. Often, much more. I’m just a guy with a camera, and progress happens only as time and budget permit.
If you’ve got ants needing reliable ID, you’ll do better consulting a site designed for species diagnosis like Antweb.org. Or better yet, use the primary literature.
…happening this evening in Urbana. Photographic evidence:
Solenopsis molesta, thief ant winged queen
Thief ants are among the most abundant insects in the midwest, but most people will never see them. They are small- only about 2mm long- and spend most of their time underground. The large relatively large size of the queens indicates a species capable of raising new colonies from workers fed entirely on the body reserves of young queens like this one. She will fly off, mate, and tunnel underground when she finds a suitable nesting site.
Incidentally, this whole drama played out on our front walkway. Urban lots can host plenty of nature for those willing to look.
Solenopsis molesta, thief ant queen
Solenopsis molesta, thief ant queen
Canon MP-E 65mm 1-5x macro lens on a Canon EOS 7D
ISO 250, f/13, 1/250 second
Diffused macro twin lite
How many ants are there in New York? The math is simple enough. We know from work that Britne Hackett and Benoit Guenard began (and Amy Savage is following up upon) that in a sample of one square meter of leaf litter there are about fifty ants, a village. Slightly more in the parks, slightly fewer in more stressed environments such as medians. But fifty is a good round starting place.
Now, how much green space is there in the city? We found one set of land use tables in which “open space” is a measure of part of the green space in the city; it does not include small patches of green such as medians or privately owned abandoned lots, but it is a starting point. If we multiply the number of ants in a square meter by the number of square meters in each borough and then double our estimate (to very conservatively account for the ants under ground at any moment) we get the following…
At a glance, those numbers don’t look great for people. But do they mean anything?
Functionally, would biomass be a more relevant comparison than body count? And, in light of the many simplifying assumptions underlying Rob’s calculation, might other methods be more accurate?
There is no way to put it delicately: it’s poop. The dark spot is at the butt end of the developing ant. But this spot is not just any old poop. It’s a rather special one called a meconium.
Although young ants have been alive and eating for many weeks by the time they spin a coccoon, they never once passed their food all the way through. Ant larvae are massively constipated. Their waste builds up in the digestive tract as a strong, concentrated mass clearly visible through their translucent bodies:
Ochetellus sp. (Victoria, Australia)
Larvae hold the pellet in as it gets larger through several molts, and don’t expel it as a meconium until they transition to the pupal stage. So, young ants only poop once.
Of course, there is good reason for the extended constipation. Living in large groups in fixed nests, ants have a public health interest in not continuously soiling their nurseries.
Speaking as an expectant father myself, I admit to a little bit of jealousy of a species that manages but a single diaper change per offspring.
Camponotus novogranadensis, as drawn by Mark Deyrup. (Adapted from Deyrup & Belmont, Figure 1).
Want to see the world’s species, but lack the wherewithal to travel to the earth’s farthest corners? You could do pretty well just visiting Florida. The state’s warm climate and constant human commerce make for an easy home-away-from-home for a staggering number of introduced species. Pythons from Asia,trees from Australia, birds from Europe, frogs from Cuba, bees from Africa, retired hominids from Wisconsin, these are just a few of the many species that have turned Florida into into a sampler of trampy biota.
An established population of a Neotropical carpenter ant, Camponotus novogranadensis Mayr, is reported from Estero, Lee County, Florida. This species is similar in general appearance to C. planatus Roger, differing in color, pilosity, and clypeal shape. Camponotus novogranadensis is known from disturbed sites in Mexico, Central and South America; it has not previously been reported established outside its presumed native range. It is not known to cause economic or ecological problems.
Having seen this ant in South America, it’s not my impression that C. novogranadensis will become much of a pest. Still, in a novel environment, all bets are off.
As an etymological aside, this ant was described from northern South America by the pioneering Austrian myrmecologist Gustav Mayr, and at the time the territory went by New Granada. Hence, novogranadensis. Or is this an entomological aside? Hmmm…
source: Deyrup, M., Belmont, R. A. 2013. First Record of a Florida Population of the Neotropical Carpenter Ant Camponotus novogranadensis (Hymenoptera: Formicidae). Florida Entomologist 96(1):283-285. 2013 doi: http://dx.doi.org/10.1653/024.096.0148
A redbud blooms along the eastern border of Konza Prairie, April 2013.
The prairies of central North America are especially harsh environments. Half a continent removed from the buffering effect of oceans, temperatures in the plains soar in summer and crash in winter. Winds, and often fires, surge across the landscape. The prairie is not an easy place.
Prairie is also an environment I don’t spend much time exploring, in spite of my current situation living as I do at their eastern edge in Illinois. So I was pleased when the entomology students at Kansas State University invited me out for a seminar last month. I spent a morning at Konza Prairie on the advice of James Trager, who had an unorthodox way of persuading me:
I hope you’ll get a chance to spend some quality time at Konza Prairie, especially in any recently burned areas, and have some good anting weather. On the several occasions I’ve been there, I’ve gotten the impression that ant abundance and diversity are both oddly low there, and you will be there at a really good time of year to check on this. I have visited there only in the heat of (a very hot) summer and early fall, less propitious times for anting.
If you’ve ever wondered why Crematogaster acrobat ants have such an odd shape, take a look at this:
Crematogaster & Pheidole, Kibale Forest, Uganda
In Uganda’s Kibale Forest last summer, I smeared a bit of cookie cream along a rock as ant bait. A pleasingly yellow Crematogaster soon arrived to feed. All was well until a second species, in the big-headed ant genus Pheidole, attempted to sneak a taste.
Crematogaster & Pheidole, Kibale Forest, Uganda
Instantly, the acrobat ant swung her agile abdomen forward - while still feeding (!) - and warded off her competition with a dab of venom. Like many myrmicines, Crematogaster has a stinger, but the structure has evolved from a piercing weapon to a soft, flexible, brush. The unique shape of the acrobat ant abdomen allows these ants to deploy their chemical weaponry in nearly any direction.
The media is carrying stories of a study in Science showing that Camponotus workers specialize into three behavioral classes, and that workers tend to move through these roles as they age. This result is interesting, but not terribly surprising as a similar pattern is known in the better-studied honey bees.
The reason the paper appears in Science, rather than a more specialized journal, is methodological. Danielle Mersch, Laurent Keller, and Alessandro Crespi have automated the observation of an ant colony. Basically, they built the perfect Orwellian ant-watching machine.
Each ant is labelled to be recognized by high-resolution video, and her position and social interactions are recorded continuously for the length of the experiment. The technique produces a staggering amount of data from relatively little effort once the initial tedious bits of gluing barcodes on ants are out of the way.
Check out just one short clip:
After extending this recording to six colonies for 41 days, Big Brother crunched the numbers:
Network analyses of over 9 million interactions revealed three distinct groups that differ in behavioral repertoires. Each group represents a functional behavioral unit with workers moving from one group to the next as they age. The rate of interactions was much higher within than between groups. The precise information on spatial and temporal distribution of all individuals permitted calculation of the expected rates of within- and between-group interactions. These values suggest that the network of interaction within colonies is primarily mediated by age-induced changes in the spatial location of workers.
The really interesting bits will come later, in my opinion, when the method is harnessed across other species. Assuming the ants don’t first figure out what we’re up to, that is.
Oak tree leafing out at Paynes Prairie State Park.
Earlier this month I gave a pair of talks at the University of Florida. The trip was fabulous! In addition to meeting a pile of exceptionally friendly people, I spent time with my myrmecologist friends Andrea Lucky and Lloyd Davis, hunting ants at Paynes Prairie State Park, Austin Cary Forest, and elsewhere around Gainesville.
Below, as promised, are a few of my photos from the visit. I’ve posted a larger set to this gallery.
Andrea Lucky and Lloyd Davis spot a Cyphomyrmex worker walking across a fire ant mound. Paynes Prairie.