Charley Barrat, who lives in Shaldon Drive, Ruislip Manor, discovered the spider - said to be a cousin of the deadly black widow spider - in her home on Tuesday, July 15.
Since then readers have contacted GetWestLondon about the spiders, urging people not to panic.
Andy Newnham, who lives in Hayes, said: "I've become quite attached to these spiders as we've noticed them on the increase in the last five or six years around us.
"We have them nesting in the porch in the spring now which requires a bit of clearing for the sake of not being overrun.
"But they really aren't dangerous so most are left alone as long as they're out of the way, and I'd certainly not evacuate or fumigate the house as they are not colonial so it's a waste of money.
"They are very very common over here in Hayes, and I have a really big female here in a jar along with a smaller male which I will release in a near-by field," he said.
A bite from a false widow or Steatoda nobilis, is said to be no worse than a wasp sting and less common.
Some victims also report feeling feverish or generally unwell as well as suffering chest pains.