New Delhi, India (CNN) -- Chotu is not happy to see visitors. He is busy scratching himself and intensely surveying his surroundings when he's approached.
He and his buddies Pinki and Mangu are in the middle of their eight-hour shifts. They have important jobs to do. They are some of more than 100,000 security forces protecting people during the Commonwealth Games in New Delhi.
But Chotu and his gang are a special force trained to put a stop to any monkeying around near the stadiums. Chotu, Pinki and Mangu are langur monkeys.
Their trainers said each one has the ability to scare off 50 potential attackers -- namely the wild smaller macaque monkeys that roam the streets and buildings of Delhi.
The wild monkeys are known for some naughty habits. You can't blame the macaques; they're just being themselves. The wild monkeys are in a densely populated city where they occasionally have run-ins with humans -- especially if there is a chance to snatch some food.
"They bite, they charge, sometimes they bite people's ears. That's why we have to use langurs," langur trainer Promod Kumar said.
Kumar has worked with langurs all his life. His father was a trainer before him. He said it takes about two years to train the long-tailed, black-faced monkeys to hop a ride on the bicycles their handlers use to take them around the city and sports stadiums.
Delhi officials said there are 10 langurs dedicated to the sports venues and a total of 38 patrolling the city.
The monkeys have plenty of work, even when the games aren't here. On a normal day, home and building owners put langurs to work against the mischievous macaques.
"The wild monkeys go inside people's homes; they open their fridges and eat the food," Kumar said.
The trainers said the macaques are afraid of the langurs and that is why they usually scatter when the lanky langurs arrive.
People often feed the macaques, especially on Tuesdays. On that day, those of the Hindu faith honor Hanuman, the half-man, half-monkey deity whom Westerners refer to as the monkey god. Visitors sometimes feed the wild monkeys, too. The macaques have gotten used to getting treats from human hands.
One of India's leading primatologists said the langurs are not the long-term solution to the monkey problem in cities. The wild monkeys just move somewhere else for a while.
Animal rights activists question using langurs for labor. The handlers said the langurs are treated like family and don't mind cracking down on their rivals' monkey business. The government itself hires them regularly.
"They're also being used in government buildings because the other monkeys go in and rip apart files," trainer Kumar said.
Imagine the government secrets macaques might know, if only they could read.