Shocked shopper Maria Layton found rare spiders inside her supermarket bananas - whose bite can give men a four-hour erection.
Maria, 43, spotted the arachnids after opening the bag of yellow fruit she bought from Tesco, in Pontardawe, South Wales.
She believed the bananas, shipped from Costa Rica, were infested with eggs from the Brazilian Wandering Spider - the most deadly in the world.
The species is deadly and its venom can kill a human in just two hours - but can also give male victims a painful four-hour erection.
As soon as Maria discovered the cocoon they started to hatch, so she quickly put them in a sealed container in the freezer and called Tesco customer services.
Its venom is currently being studied for use in erectile dysfunction treatments.
Mother-of-two Maria went to open the bag for her eldest daughter Siri, six, but noticed there was something funny on the side of one of the bananas.
Maria, a full-time mum from Westbury-on-Trym, Bristol, said: 'My husband bought the bananas from Tesco, they had been in the house a whole day before I ripped the bag open.
'Siri asked for a banana. The first banana had a funny bit on it, so I got another one for her and that was when I found the massive spider cocoon.
'There was a spider web on the other bananas too.
'I was so scared - I don't like spiders at the best of times, but have read about the Brazilian Wandering Spiders - and was very frightened about the potential threat.
'The spider cocoon started to unfurl so I put it in a sealed box and put it in the freezer as I read that that is supposed to kill them.
'I'm glad it was me rather than Siri that opened the bananas, I think the spiders are more likely to bite small children rather than older people.'
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The Brazilian Wandering Spider are mainly active during the night, and walk across the jungle floor.
But during the day they hide inside banana plants hence the nickname 'banana spider'.
Shocked by her discovery, and the threat to her and her children - Siri, six, and Phoebe, three, Maria contacted Tesco customer services.
Tesco said that Maria should bring the bananas, deadly spiders and all, back to the store so that the bar code could be scanned and her money refunded.
Maria said: 'Tesco were a bit useless, I was really concerned about the possibility of this dangerous spider and spider eggs in my house and really wanted some helpful advice on how to act.’
A Tesco spokesperson said: ''We've apologised to Mrs Layton and offered a gesture of goodwill.
'We've asked her to return the product to our store so we can conduct a full investigation.'