A tiny larva came to a sticky end, 370 million years ago, when it plunged into a shrimp-infested swamp and drowned.

Unearthed in modern-day Belgium, the humble bug now looks set to plug a giant gap in the fossil record.

Named Strudiella devonica, the eight-millimetre invertebrate - while in far from mint condition - is thought by researchers who published their findings in Nature to be the world's oldest complete insect fossil.

"It has everything an insect should have: the legs, the antennae, the thorax and the abdomen," says Andre Nel of France's National History Museum, one of the authors of the study.

Scientists until now had few if any confirmed insect fossils from between 385 and 325 million years ago, a period known as the Hexapoda Gap, writes William A Shear of Hampden-Sydney College in a commentary that accompanied the study.

Strudiella devonica could significantly narrow that gap in the fossil record.

Based on molecular DNA studies, Nel says scientists had long expected to find insect life dating that far back, but the fossil find yields insight into the evolutionary roots of the insect kingdom.

"Insects are an extremely ancient group, but we know very little about the earliest among them," he says. "This find enables us to confirm our molecular dating, it's a paleontological marker."