Monday, June 20, 2011

On a Saipan beach: Attack of the winged ants

We joined several friends at the beach yesterday afternoon.  Our fun in the sun (and rain) was interrupted by a hoard of itching insects.  Photographs show that they are ants.

[An email exchange over the course of a single day (June 21--coincidentally, the Summer Solstice) has led to something of an understanding about what this ant may be---or at least a general direction to look at.  In the interest of accuracy, I am revising this post.]

Possibly they are Solenopsis geminata winged males.   [Wrong on two points---they are not males, and they are not members of genus Solenpsis]  They may belong to genus Hypoponera, and they are apparently reproductive females.  An expert, Cas Vanderwoude, hasthis to say about this genus:
Whatever it is, it’s a Ponerine.  All Ponerines have painful stings – some are reluctant to use it but others are more than happy to give you a jab or 2.

Their stings bothered some members of our Fathers' Day party at Paupau Beach, while others were not bitten at all.

James Wetterer, who has taken on the task of cataloguing the ants of the Marianas, has forwarded an apparently unpublished list, with the following three members of genus Hypoponera listed:

At the site, was found some fundamentals. We had wondered whether this was a fire ant, when it was black. With red legs. The workers of Solenopsis geminata are red. Writing about S. invictus, which (hopefully) we do NOT have on Saipan, the writers of that page made the following comments on the coloration of adults of various guilds:
The red imported fire ant is the most common and troublesome species of ant in the southeastern United States. The worker (wingless female) is reddish or dark brown and may be large (6 mm) or small (3 mm). Winged males are black and have colorless to pale brown wing veins. Winged females are mostly light brown. Distinguishing among species of ants in the genus Solenopsis is difficult.

I'm inclined to think that is what we have here.

  1. Hypoponera confinis (Roger)   Tinian, from specimens.

  2.  Hypoponera pruinosa (Emery)  Tinian and Papago, Saipan, both from specimens.

  3. Hypoponera punctatissima (Roger) Guam and Asuncion, from published records.

 The latter species has been noted as an invasive tramp species, elsewhere. 

Aubrey Moore has contributed further:
Were these ants stinging you? If so, they were females. The stinger is a modified ovipositor, so only females can sting.

Leading me to be even more cautious, Google teaches that in some ants, reproductive (winged) females may be dimorphic: Solenopsis spp. have macrogyne and microgyne populations, that make nuptial flights at different times of year.

Two days later, Fe is still suffering from intense itching: when someone touches one of the swollen bites (some of which are starting to develop white heads), she reports that these bites all over her body itch intensely.   Mainly, on her back, back of the neck especially, and a couple on her arms.  I was also attacked, but my reptilian skin seems to protect me better: only a couple of bites have swollen up.   Fe says she was wearing perfume that day: she was clearly the most seriously affected, as she sat in the water for an hour or two, writhing in discomfort.   They swarmed all over the back of my (red) shirt, and some others were bitten, and in at least one case, the bites subsided within a day.

This is clearly a seasonal event, and quite probably lunar.  Winged ants of another species,  a carpenter ant (Camponotus cf. chloroticus) swarmed out of the sill of the front door of our apartment on the same night.   They are still bothering me two days later (just like their workers do, all the time.)

Tuesday, June 14, 2011

History of San Francisco Bay as Estuary

I've started digging around, trying to get a sense of our new home.  I've lived in the Bay Area before, but never with a naturalist's eye.  Now I stumble upon a consumately well written piece by none other than the great Joel Hedgepeth: San Francisco Bay: The Unsuspected Estuary, available here.
For nearly 200 years, Spanish navigators sailed the Manila galleons from Acapulco, northward past the unseen Golden Gate of San Francisco Bay, to Cape Mendocino whence they turned westward across the Pacific. It was not until 1769 that European explorers and "men of God" discovered the Bay, not from the sea by entering the Golden Gate, but from a hill to the south.

This paper, dated 1979, provides an appealing and broad coverage of the early history of naturalistic study of the Bay, and of the Bay's abuses at the hand of modern man.  This goes with me on the plane.  Here's one of the earlier pioneers, Grove Karl Gilbert:

[caption id="attachment_43" align="alignright" width="234" caption="From the PDF."][/caption]