No, they just fly about and eat flies, Tens of million of them from all over Europe and Russia make their way to South Africa and Southern Nambia for a giant get-together. Then around the end of Feb they all make their way back to where they were born.
I Didnt kill them just deported. They are related to the Redback we had them in our garage in QLD I didn't want to but had to kill them as my Dog would chew anything.