Huh, I just found out that the flying rods are, in fact, not real creatures. Well, they are real, but it's just normal insects, like flies and moths, that get this weird shape on photos, because they're so fast, they get overexposed on photos and videos (look up low shutter speed, or over-exposure photography), so the bodies get distorted in length. You can see it captured clearly in the following video; at some point the 'rods' become regular flies, when they fly towards the camera (skip to minute 3:10): https://www.youtube.com/watch?v=X88ZtcRwlLk
The weird sinewave shape of those 'rods' are explained in the following text I found:
"As you might expect, there is indeed an alternate explanation, and a simple procedure to take a picture showing rods. Imagine yourself standing with the sun at your back, facing a large shaded area, such as the shaded entrance to a cave. Dragonflies (or other insects) are flying everywhere, darting back and forth at around 9 meters per second. Take a photograph, with a common shutter speed of 1/30th of a second. In that time, the dragonfly will travel about 30 centimeters. Because your exposure is set for the dark background, the path traced by the dragonfly's transit will be overexposed and will appear solid white. Dragonflies beat their wings about 30 times a second, so the path described by its wingtip on your film image would be one full sine wave period, 30 centimeters long. There would be one of these sine waves down each side of the 30-centimeter-long rod shaped track traced by the dragonfly's moving body. Change these parameters with different insects, different wing speeds, different camera shutter speeds, and you can duplicate any rod photograph on the Internet."