Casino-goers in Las Vegas had a surprise after a swarm of grasshoppers took over the city's famous strip.

Thousands of the invertebrates were filmed gathering around neon lights outside gambling venues over the weekend.

The influx of grasshoppers is being attributed to wet weather several months ago which created ideal conditions for the insects, leading to the explosion in numbers.

Nevada state entomologist Jeff Knight said the number of adult pallid-winged grasshoppers traveling north to central Nevada is unusual but not unprecedented.

He added they do not pose any danger.

Thousands of the grasshoppers were spotted in the city over the weekend. Credit: AP

Mr Knight said the insects don't carry disease, don't bite, and probably won't damage anybody's gardens before they're gone in several weeks.

He said they're usually attracted to ultraviolet light sources - so Las Vegas presents the perfect attraction for the bugs.

Over the past 30 years, similar migrations have happened including one six years ago.

This year, the Las Vegas area recorded more rain in six months than the annual average of just under 4.2 inches (10.7 centimeters) per year.