NEW DELHI — The first interloper stepped in front of her on the sidewalk and silently held up his hand. The second appeared behind her and beckoned for her bag. Maeve O’Connor was trapped.

Resistance would have been dangerous, so Ms. O’Connor handed it over. The two then sauntered arrogantly away. The whole encounter lasted no more than 15 seconds — just one more coordinated mugging by rhesus monkeys in a city increasingly plagued by them.

“I had other bags with me, but they knew the bag that had the fresh bread in it,” Ms. O’Connor said.

“They were totally silent, very quick and highly effective.”

The monkey population of Delhi has grown so large and aggressive that overwhelmed city officials have petitioned India’s Supreme Court to relieve them of the task of monkey control.