UK supermarket retailer Tesco has denied it has been using black widow spiders as a form of pest control after three customers found the deadly spiders in bags of grapes within the last few weeks. In one incident, Stephanie Thorneycroft of Wimbourne in Dorset spotted a black widow spider in her colander as she washed the Tesco American-grown grapes. Two similar incidents occurred – one in Merseyside and another also in Dorset.