Today, I saw one of the strangest phenomena I’ve ever seen. Stictia signata is a pretty common wasp species here where I live (particularly at beaches, but less common in the woods), and today I was at a parking lot close to a forest, and on an area with some sandy-looking soil, dozens of these wasps were flying like crazy. This is so weird, I’ve seen them digging their nests before solitarily, but what went on here? I don’t think this was a mating frenzy because they were just… flying dumbly around that single spot, doing nothing! I also thought about a possible mass emergence occurring at that moment, but I waited for a while to see if they were flying away, but they never left! After a while they were still dancing there doing nothing! Something else that surprised me is the amount of burrows there. There were dozens of wasps, but only two or three holes!!! What were they doing? And then, suddenly, some started digging on the ground, and ONE only entered to a hole hiding in leaf litter. The ones that started digging (one of them carrying a fly) just did so for a few seconds flying away again leaving the soil intact (and the one with her fly had to carry her prey to somewhere else). I tried to video this but the wasps were flying too fast, anyway I haven’t checked the videos yet (hehehe).
Any opinion, hypothesis or theory is appreciated. Thanks.
And what about gregarious nesting? Yes, I’ve always seen them nesting in complete solitude, but maybe they have at least some level of gregariousness, who knows…
I have seen aggregations of male Sycophila wasps waiting for females to emerge from figs, and I suspect that you saw something similar. I am no hymenopterist, but my suspicion is supported by this paper - Post, D.C., 1981. Observations on female nesting and male behavior of Stictia signata (Hymenoptera: Sphecidae) in Brazil. Revista de Biologia Tropical , 29 (1), pp.105-113. https://revistas.ucr.ac.cr/index.php/rbt/article/view/25520
Not very sure, I’m sure many of them were already females, as I said, I saw some trying to dig holes and one was carrying a fly. And one of them even entered to a hole.
It could be possible that there is a larger nest underground, or that all of the flying ones are males waiting for females to emerge. It would probably be helpful to see the video if you have it.
This doesn’t sound like a male aggregation to me. I would look into whether there are parasites that affect behavior this way, or chemical contaminants.
