We had some friends round for a BBQ yesterday. They noticed a crazy looking web in the corner of the garden, and were pretty sure it belonged to a black widow. Sure enough, come dusk, the spider came out of its lair in the corner of the web. A quick spray with spider spray dispatched it and ensured that the same spot wouldn't be used by another tenant for a while. There was another similar web in another corner of the garden, with another, smaller black widow.
I do feel a bit bad, spraying spiders, but we have two small children, and black widow venom is highly neurotoxic.