I'm A Celebrity... Get Me Out of Here! stars will face more than 120,000 critters on their first Bushtucker Trial - a record for the ITV show.
Gogglebox star Scarlett Moffatt, 25, ex-Strictly professional Ola Jordan, 34, Diversity dancer Jordan Banjo, 23, and Olympic gold medal winner Sam Quek, 28, will face the Tomb of Torment on Monday.
They will lie down in a tiny "deserted tomb" in the depths of the jungle, before being joined by rats, mealworms, spiders, crickets and cockroaches.
The celebrities will be hoping to win 10 stars for the camp.
The four are facing the largest number of critters used for a single trial in the show's long history, after failing the Saviours Challenge.
Meanwhile, the jungle reality show opened its 16th series with its own presidential election.
Fans of the show have been asked to use the ITV programme's app to choose a camp president and vice president who will be able to dish out chores to their fellow contestants.
As presenters Ant and Dec explained the vote, Dec said: "Don't worry, they haven't got any nuclear codes and they're not going to build a wall between the camp and the rest of Australia."
Sunday night's debut episode saw TV presenter and mathematician Carol Vorderman, Emmerdale actor Adam Thomas, comedian Joel Dommett, actor Larry Lamb, ex-footballer Wayne Bridge and radio presenter Lisa Snowdon enter the Australian jungle, along with Scarlett, Ola, Jordan and Sam.
Carol, Jordan, Adam, Joel and Ola were asked to choose a celebrity from the remaining five to be paired with before they met in person.
Each half of every celebrity couple then tried to do well enough in a challenge to win their partner immunity from the first Bushtucker Trial.
The five pickers were made to walk a plank suspended 334 feet in the air from the roof of a Gold Coast hotel and try to estimate as close to 60 seconds as possible standing at the end of it.
Unsurprisingly, maths whiz Carol won and said: "It would have been very embarrassing if I didn't get the closest to 60 seconds, really embarrassing."
Meanwhile, Lisa, Wayne and Sam jumped out of a plane with the aim of skydiving as close as possible to a marker on the ground, while Larry and Scarlett had to canoe into the jungle and hoist a flag as quickly as possible.
Scarlett struggled with the task as her canoe sank, leaving her clinging to a raft in the water as Larry dived back in to get her.
She said: "He's not like your average 70-year-old, he's superhuman.
"I've had to be saved by Larry Lamb because I can't swim, I'll never live this down."
Ola, Jordan , Sam and Scarlett all went through to the first Bushtucker Trial.
I'm A Celebrity... Get Me Out Of Here! continues on Monday night on ITV at 9pm.