|Solenopsis xyloni (Southern Fire Ant)|
|Polymorph workers: many different sizes|
But our little guys can sting too. When they come to my black light at night to tackle any small scarab that falls and lands on its back, they sometimes also get my toes. They seem to always plan their attacks until several are in position ... just like their bigger relatives in Florida. Their stings burn and itch but are really just a minor irritation. In our kitchen they were so docile that I first doubted my identification. No attempts at stinging at all.
|Tackling a Minute Black Scavenger fly|
|Southern Fire Ants in the compost bin|
|Southern Fire Ant on a barrel cactus fruit|
|At nigh at my black light site: Southern Fire Ants taking apart a scarab beetle and gorging on sweet saguaro pulp|
When I returned the Fire Ants had performed to expectations: not only did they overpower a small scarab beetle (Acoma sp.) and were just testing the resilience of a much larger Oxygrylius, they were also all over my saguaro offering.
I know that the time of day and temperatures also play an important role in an ant's activity, but I did find Solenopsis xyloni active in the afternoon on the barrels but not the saguaro. Since they obviously love the saguaro fruit, I am back to my idea that there simply is no colony close to the free-standing saguaro. Why?
To the human eye areas around the barrels and the columnar giant looks quite similar. So is it the cacti themselves that make the difference? Their yearly cycles are quite different. The saguaro blooms in April/May, and has fruit in June. As far as I can tell, those are the only times when saguaros have anything to offer to ants.
|Barrel Cactus, this year's flowers and buds surrounded by last year's fruit|
Barrel cacti also offer sweet sap from extra-floral nectaries all year round. It could be that the barrel cacti (via coevolution) are 'making sure' that ants have a reason to hang around. The cacti may be employing armies of little fighters for their protection against other bugs and the distribution of their seeds by offering them sweets. I have seen the ants attack cactus-juice-sucking coreid nymphs in several cases.
|A jumping spider killing a coreid nymph on a barrel cactus|
Barrels are very vulnerable to rodents so they are tightly covered by a mail of interlocking thorns. This formidable defense may keep many birds from spending too much time on a barrel, and at any rate barrels are not tall enough to provide protective spaces for nests. Ants and spiders however have the ideal size and agility to police that space under thorns and between ribs.
Both saguaro and barrel cacti eke out a living in spartan surroundings. There is not much more than sand, widely spaced creosote bushes and cholla cacti. Under these borderline conditions the reliable yearlong provider may win out over the once-in-a-year party host when the opportunistic Fire Ants are choosing a neighborhood to live in.
|Pheidole sp. left and Messor pergandei right. Colonies close to the saguaro|
With this blog, I would like to stress that not all ants are alike, every species has its own ecological niche, and not even all Fire Ants are alike. The imported, highly invasive Red Fire Ants are established all the way from Florida into Texas in the east and in California in the west. But they need more moisture than they would find in southern Arizona and they may be too frost sensitive to live on the Colorado Plateau in the north. So they may never overrun Arizona.
Living with ants (and you will, if you live in Arizona) is easier and far more interesting if you learn about the different types, one species at a time. Theirs is a densely populated and highly socially organized world to discover.
Please do not contact me about methods 'to get rid of ants'. I have no experience in that field and - beyond my own kitchen counter - no interest in gaining any.