Crematogaster atkinsoni

Crematogaster is a name of controversial origin.  As spelled, it means burning stomach.   But they don’t need Nexium… the name probably originated from cremasto-.  Cremasto– means “suspended,” as in “cremaster,” the stalk suspending a butterfly chrysalis. The ant in its defensive mood arches its “stomach” (abdomen) suspended up over its head with its stinger facing forward, thus the name Acrobat Ants.  The stinger does not sting, but instead is a spatula for dabbing toxins onto foe.   They can bite too.   Professor George Atkinson (1854-1918) was a prominent U.S. entomologist.

Carton nest in Hypericum

Around South Florida and beyond, a curious sort of ant nest decorates marshes, in John’s and my experience mostly the depression ponds dominated by Peelbark St. Johnswort (Hypericum fasciculatum) and Corkwood (Stillingia aquatica).  These “carton” nests are gray and papery resembling hornet nests in color and texture. The cartons range in size from a tennis ball to a cucumber, up on a host plant, usually Hypericum around here, safe and dry above the high-water level.

Don’t touch, we are nice but will bite if abused..

It was Professor George Atkinson who first described the nests in 1887, attributing them incorrectly to ant species not otherwise known to such constructive feats.  Something wrong there!

Ant nests don’t get much attention, and the next leap forward waited until 1919 when Harvard Professor William Morton Wheeler discovered the nest dwellers to be a previously undescribed species he named C. atkinsoni.  The species is especially fond of periodically inundated open marshy habitats usually near the sea.   Recently some entomologists reclassified C. atkinsoni as a variant of another species, C. laeviuscula, although an objection to the demeaning merger is the unique nest-building by C. atkinsoni.   Around the world, varied ants, including other species of Crematogaster, make carton nests broadly defined, but in the Southeastern U.S.,   C. atkinsoni has a monopoly.

I live here.

To this day, the ant and its nests seems under-studied, at least as far as I can tell on Google. What does an ant colony in a paper box perched isolated above the flooded marsh eat?   What are its seasonal cycles? Given the abilities of tropical carton-nest ants, there are multiple possible answers on how to “get provisions” during high-water lockdown.  Your guess is as good as mine, although look twice at numbers 4 and 5:

1. Capture food before the flooded season and store it in the nest?
2. Capture insects or seeds visiting the host plant, or visiting neighbor plants accessible by leaf and stem bridges? (Even in high water the crowded plants touch each other so it is possible to get around a good bit.  C. atkinsoni has been reported to eat other insects.)
3. Cultivate seeds in the nest? (Ants are known to nibble growing roots from seedlings in their nests. Some epiphytes establish in tropical “ant gardens.”)
4. Cultivate fungi? (This is likely the (or a partial) answer…some non-U.S. species of Crematogaster cultivate fungi, including yeasts, on the carton material itself. Looking into this would be an interesting research project, by taking “biopsies” from the nest for laboratory culturing without destroying the colonies.)
5. Farm sucking insects for their honeydew? (Other species of Crematogaster in other tropical habitats farm scale insects in their nests, and UF entomologist W. Whitcomb reported varied Florida crematogasters associating with aphids.)
6. Wait it out, perhaps with some adult die-off?

Might be possible to find this out, and to a point is a tempting research project, but not if you’d have to poison the ants and destroy the nests. The nests are rare, complex, and beautiful, not to mention in protected natural areas.   Better to leave something to the imagination.