Years ago when I was in the US army in Germany, I was stationed in the small town of Babenhausen. Behind the rear of the post was a large forest with many interesting trails. On some weekends when I didn’t have a pass to get off post, I would go out back, climb the fence, and explore these various meanderings. There was a wide variety of wildlife to be observed, and occasionally one might see a deer or wild boar.
On several of these excursions I would come upon these giant ant hills. They were upwards of three foot tall or more! They seemed to be mostly composed of pine needles, and they were swarming with activity. Around the perimeter of the hill there was a small trench, lightly filled with leaves, twigs, and more pine needles. It seemed to be constructed so that if some unfortunate small animal came too close it would fall into the trap. At which time the creature would be instantly covered by the ants, and stung into submission. It was kind of shocking how quickly this would take place. In some places there were several of these hills in the same area.
I couldn’t help but imagining the macabre image of someone stumbling on to one of these on a foggy day. One could lose their footing and fall; whereupon the hapless victim would be quickly enveloped, and perhaps paralyzed by this horde of tiny hunters. Fortunately, I never heard of any such occurance. But I always made it a point to do my exploring on a bright and sunny day.

commons.wikimedia.org/wiki/Ant_hill by Guido Guerding