Don't be fooled by the red dot on the top of the body - this is still a Black Widow spider! This is a species marking variation - there is still the shiny black and red coloring and the distinctive shape of the Black Widow body. This is not a harmless arachnid, but a Black Widow spider.
Black Widow spiders are known to man not just for their dangerous venom, but for the strength of the silk they weave their webs with. Their webbing is incredibly strong, and scientists have recently been studying its composition in attempts to replicate it. Although silkworms have been farmed for centuries, it is completely out of the question to farm Black Widow spiders. Black Widow spiders are far too dangerous and spiders in general, too aggressive, to keep en masse and collect silk from.
If you ever walk into a Widow's web, you will know it by the distinctive snap sound that the web will make as it breaks. Usually webbing innocuously but annoyingly sticks to you like a thread or a hair, without any indication of exactly where you picked it up. A Black Widow's webbing is more like a fishing line than a thread, and very visible-a cloudy white. The Black Widow web strength is comparable to steel or Kevlar. This kind of lightweight strength would be useful to make aircraft, and for the things that Kevlar is now used for - bullet-proof vests, parachute cords - Kevlar is an inferior material to Black Widow silk. Scientists have had some success in copying the Widow's silk, but it is a work in progress.
As dangerous as it is to people, studies of Black Widow venom show that it could have potential to make a pesticide that would leave no residue. There are indications that the venom may be useful to Alzheimer and Cancer patients.
There is no final word on these scientific possibilities - research is ongoing. in the meantime, check your grapes before you bring them home. Apparently, Black Widow infestation of table grapes is a serious problem.
