- We have a number in our garden that we love to see come out. Today, one showed behaviour I have never seen before. It was wrapping a catch up in silk and these little black flies were trying to get to the catch and were landing on the catch and the spider. The spider was aggressively swatting the flies away, espeically when they landed it. It would even turn around and swat them in the air. Eventually was satisfied with the wrapping and moved to the side of the web to watch them. Tried to video it but was all over before I got back with the camera.