Here’s how Knab explained it: males gather around some landmark—a cornstalk, perhaps the head of an unsuspecting human–and wait for eligible females. When a female enters the swarm, the males immediately pick up her flight tone, which is different from theirs. Coupled with one lucky guy, she flies to some protected place to mate. After their interlude, the female goes to lay her eggs, but the male returns to the swarm, on the outside chance that he’ll get lucky once more. That’s why Knab netted so many more males than females. Sometimes, these gatherings get quite large. In Germany, in 1807, people saw a huge cloud of smoke billowing over a church. So they called in the fire brigade, only to realize that the dark cloud was actually a swarm of gnats who’d picked the church steeple as their rendezvous.

下面是Knab对这一现象的解释：雄性聚集在周围的一些地界标上——比如玉米秸秆，也许是不知情的人的头部——等待合适的雌性。当雌性进入昆虫群时，雄性的飞行状况马上变成和雌性的一样，这和雄性本来的飞行是不同的。和一个幸运的雄性配对后，雌性会飞到受保护的地方进行交配。这段插曲过后，雌性去下蛋，但雄性会飞回原地，它还有极小的机会再次得到配偶。这就是为什么Knab捕到的雄性蚊子远多于雌性。有时，这些昆虫聚集会很大。1807年在德国，人们看到了滚滚浓烟在教堂上翻滚。因此，他们给消防大队打电话，后才才弄白乌云实际上是一大群飞虫，它们将教堂的尖顶作为约会地点。