The world’s oldest bug has been discovered on a Scottish island.

The 425-million-year-old millipede fossil is older than any insect, spider or other creepy crawly ever recorded.

It has caused scientists to rethink how bugs and plants evolved, suggesting it was more rapidly than previously thought.

They are now believed to have moved from lakes to complex forests in just 40 million years.

Researchers at the University of Texas in Austin, US, made the discovery while exploring Kerrera in the Scottish Inner Hebrides.

They used a “delicate” technique involving extracting microscopic minerals from the rock sediment which the fossil was preserved in.

Once the minerals, known as zircons, were released from the surrounding rock, the team were on an “eagle-eyed hunt” with a pin glued to the tip of a pencil.

Analysis determined the ancient millipede fossil is 425 million years old - about 75 million years younger than the age other scientists had estimated the oldest to be.

And other research using similar fossil dating methods found the oldest

fossil of a land-dwelling stemmed plant - also from Scotland - to be the same age.

The improved dating technique was fine-tuned by Stephanie Suarez, a doctoral student at the University of Houston.

She had previously used the technique to find that a different millipede specimen, thought to be the oldest bug at the time, was about 14 million years younger than estimated - a discovery that stripped it of the title of oldest bug.

The team used the same technique in this study to pass the crown to a new specimen and to gain new insight into the origin and rapid evolution of bugs and plants.

Michael Brookfield, research associate at UT Austin’s Jackson School of Geosciences and adjunct professor at the University of Massachusetts Boston, said: “It’s a big jump from these tiny guys to very complex forest communities, and in the scheme of things, it didn’t take that long.

“It seems to be a rapid radiation of evolution from these mountain valleys, down to the lowlands, and then worldwide after that.”

The authors believe there could be older bug and plant fossils out there, but they have not been discovered - even in areas known for preserving delicate fossils from the same era.

The findings were published in the journal Historical Biology.