The first part of this ongoing saga is here. Pics were taken at dusk, so may not be optimal.
At dusk I returned and the Pheidole megacephala (PM) were trying to reform the trail (line) it had from the north to the node located under the vegetation (see Image 2). A line of PM from the vegetation node slowly moved forward, while another line from the north moved hesitantly towards them from the pavement. I left when the two finally consolidated and a stream of PM moved back and forth. No fire ants were in evidence.
However, when I returned maybe an hour later, streams of large fire ant workers were moving all over the same black spot as this morning, with more lines stretching north (see Image 2). The fire ants were very aggressive, and kept trying to enter into the crevices between the pavement, where the PM huddled (see Images 1 and 3). The trail between the north and the PM node under the vegetation was gone, and almost no PM was above ground, except for a few fighting soldiers.
A few fights between the fire ants and soldiers had broken out. At least 2 PM soldiers were killed, stung to death or crushed by the large fire ants (see Images 5 and 6).
The fire ants definitely were the more aggressive, and on offense. They kept trying to enter the tunnel where the PM huddled, and there was probably fighting in there.
I saw one PM soldier on the surface just standing stock still (see Image 7), its gaster seemingly vibrating. It was probably releasing some alarm signal or some chemical deterrent which caused the fire ants not to touch it (at least temporarily). There were no signs of PM minors in the exposed upper surface. Most of the fire ants were the larger individuals, some of which dwarfed the PM soldiers, and pointed towards some specificity when it came to the fighting roles in this species.
Looking around some more, I noticed that the flow of PM from the north had become stronger (see Image 2). Instead of absconding or retreating, it was obvious that the PM were simply sending more and more workers to the scene from a more central node (remember that this scene is at the periphery of the PM cluster). The trail went along the crevices between pavement concrete, which I noticed frequently had roofs made of soil (see Image 8 below)
Unfortunately, I had to leave by around 8 pm, with night fast approaching. When I got back around 10 pm, there was no fighting above ground and only maybe 2 fire ants on the surface (black spot area on Image 2). The strong lines of PM from the north continued (and in fact the flow of ants streaming down seemed much stronger).
The next morning, at around 7 am, I visited the location again. The PM had reformed the connection to the PM node in the vegetation, there was still a strong flow of PM along the north line, and a second less dense line (also from the north) had formed as well (see Image 9). There was no evidence of any of the fire ant trails or any individuals around the area. A small mound to the side of the pavement (under the vegetation) where fire ants had been issuing from yesterday now had PM soldiers and minors around it.
Any fire ants entering the tunnels of the PM likely perished underground overnight, their bodies spread then dismembered, and the moving colony probably withdrew or moved away after failing to force the PM to abscond.
UPDATE (2024-06-26): I checked again at 7 pm tonight. There was no evidence of fire ants, and the PM lines to the vegetation node as well as the line from the north was flowing, albeit not as heavily as yesterday.
UPDATE (2024-06-27): No signs of fire ants in the location when checked at 7 am. At this point, unless some changes occur, will treat as a done issue.
Update (2024-06-28): Baiting in am revealed that the fire ants are meters south of the PM node (which is around where I had them a half month ago). So what might have happened is they tried to move a part of their colony into the space occupied by the PM and could not.
Update (2024-07-04): Pm now is back to having foragers all the way south to bait/border #3, which was where they had been farthest before the fire ant incursion. I have not seen any fire ant foragers the last few days, although Paratrechina sp/Nylanderia sp are competing for baits with the Pm now (they are opportunists, so get to baits fast, but are ultimately driven away).
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