Sophie Harris, aged four, of Baschurch, was left with a painful black wound after being nipped by the false widow.
But the youngster, who attends St John The Baptist Primary School in Ruyton-XI-Towns, made a full recovery after her quick-thinking mother Amy squeezed out the venom.
Miss Harris, 28, found hammock shaped webs full of the creepy crawlies in her porch and garden fence and now worries her sons, one-year-old Thomas and two-year-old Alfie, will also be bitten.
The arachnid, said to be spreading further north due to warmer temperatures, has the worst bite of every spider species in the country.
Eight spiders, thought to be false widows, were spotted at the Shrewsbury home of former Sundorne councillor Karen Burgoyne on two separate occasions last week.
And last week Devon amateur footballer Steve Harris had to undergo emergency surgery on his leg after being bitten by one as he slept.
Sophie's mother said she panicked and popped the black boil in a bid to rid her daughter of the venom.
"She had come back from school, I had got her undressed and then she complained of having something hurting her on her back," said Miss Harris, of Prescott Court.
"When I looked I discovered a lump of black in the middle with yellow around the outside about the size of a 5p piece.
"I took her to the Royal Shrewsbury Hospital but they didn't have a clue about this spider.
"They just said take her home and give her some Piriton.
"She said a spider bit her but because she is four and she's got a wild imagination I didn't know whether to believe her.
"But that evening in the porch way of our house we noticed lots of hammock-shaped webs.
"There were quite a few so I took a closer look and saw these spiders with skull-like markings on their backs.
"I looked them up and the more I read about them the more I worried. "She was in a lot of pain with a temperature and was sleepy and upset as it was really hurting her.
"I didn't know what would happen if I left it. I just panicked thinking if this poison is still in her and I leave it it's going to get worse and she might have to get operated on.
"So in the end I squeezed it." Miss Harris killed the spiders and their webs but is worried that they will return and bite her children.
She said: "Thomas isn't walking yet so I'm not letting him on the floor as much as I would do because I don't know if I've got them all.
"It's a big worry. There's loads of black bits and I don't know if they are eggs so I'm going to keep an eye on them in case it hasn't killed them all off.
"The more I've heard about them and the people who have been bitten and needed surgery I felt really lucky that hers didn't get to that with Sophie."