Invasion of the false black widow

As the weather heats up again and you kick off your flip-flops, watch your step. You could risk a nasty nip from any of several fierce creatures which thrive in extreme heat.

As Britain swelters under the impact of climate change, exotic spiders, scorpions and snakes are taking hold in the heat.

In the past few weeks, the first colony of a black widow-like spider was found as far north as Scotland. The "false black widow", which can give a painful bite although it is not poisonous, is more usually found in the baking heat of places such as Mexico.

Other members of the arachnid family are on the march too. The wasp spider, once confined to a narrow band of southern England, has travelled as far as Lincolnshire in recent years as temperatures edge up year by year.

The adder, the UK's only venomous snake, which grows up to 2ft, is also plentiful, with an estimated 130,000 wriggling around, mainly in central, east and north-west England.

Scorpions are also a worry. There have been occasional hitch-hikers among food cargoes but they now have an increased likelihood of surviving in the warmth, with reports of nests in places such as Liverpool. But because they are not airborne, their ability to spread is limited.

The UK has already proved itself to be a suitable environment for some types of scorpion. Two colonies are established in the Thames estuary area, probably from a docking ship. "They are only about an inch long and the sting is only as bad as the nip you get from a red ant," said Roger Key, a senior invertebrate ecologist at English Nature.

Europe's largest solitary bee, the carpenter, is also becoming more prevalent as Britain develops a climate more in tune with its European neighbours. "The carpenter bee is about the size of a queen bee and is jet black with a blueish tinge," said Mr Key. "It looks pretty fierce but it is unlikely to sting."

And harmless insects are doing well, too. Several types of dragonflies are on the rise, including the lesser emperor and red-veined darter, both more commonly seen in southern Europe.

Gardeners have reported new varieties of vine weevils which can wreak havoc on plants, and they have also spotted the rosemary leaf beetle, which is particularly partial to rosemary and lavender.

"It certainly seems to be climate change which is helping these species," Mr Key said. "I wouldn't be surprised if we begin to see the praying mantis established in a few years. I'm actually surprised we haven't already seen it."