A spider expert from Sussex believes warmer weather has resulted in a growth in the number of immigrant spiders in the south of England over the summer.
The false widow spider looks similar to the deadly black widow
Angela Hale, 44, from Eastbourne, has received about 30 calls from gardeners reporting false widow and wasp spiders.
She said: "They are pregnant and bigger at this time of year. They are not dangerous. Just enjoy them."
Warmer weather had meant more insects for the spiders to eat and gardeners working later into the year, she added.
Ms Hale, who works for Drusillas Zoo near Alfriston, East Sussex, said the false widow spiders and wasp spiders originate from mainland Europe but are no more dangerous than the garden spider.
False widow spiders look similar to the deadly black widow and have reached British shores via shipments of fruit, she said.
"False widows don't have the distinctive red marking which looks like an hourglass underneath them that black widows have," she said.
Ms Hale, who is secretary of the British Tarantula Society and owns about 100 tarantulas, said wasp spiders get to the south coast by being blown by wind across the English Channel.
"The bite of a false widow or wasp spider is no worse than a bee or wasp sting," she said.
"False widows have been in Britain for quite a while but wasp spiders are a more recent arrival."
She said she had also received calls from gardeners concerned about spiders which were in fact garden spiders carrying eggs.