Police say the thieves are typically drawn by the presence of an iPhone and a distracted victim.
The so-called "Apple pickers" have been at it since before the holidays and sometimes work in pairs.
After nearly 40 attacks, the pattern is pretty clear. The victim is alone with a phone in broad daylight. The victim is almost always a woman - all except for one case - and the phone is always an Apple, CBS New York reports.
The victims seldom get a look at who robs them because the suspects are usually on a bicycle so they can flee the scene quickly.
Security apps on the phones are disabled quickly and only a few of the robberies have been caught on video, so police have little to go on.
Police believe each iPhone goes for $150 to $200 on the streets.
As time goes on, the thieves seem to be getting bolder, according to the station. Police are urging everyone not to get so wrapped up in phone conversations that they look like easy prey.
Police are expanding their investigation to include iPhone thefts from local restaurants in the hope of getting better security video of the thieves.