Have Thief Ants Escaped?

In a recent trip to western New York, I noticed a trend. Whenever I found an ant colony (flipping rocks looking for bait for a family member who likes to fish)…


an ant colony like these cornfield ants…


I found thief ants.




Take these Lasius.



Can you see the thief ants?


Let me give you clues. The thief ant is in the top right of first photo, near cluster of three larvae in second photo, and going into the tunnel just left of center in the last photograph.

Thief ants are named for their tendency to live with or near other ant colonies and then steal food from their “hosts.”

They can also be found living in separate colonies.


Some of the thief ant colonies I found living by themselves were quite large.



Looks like quite a few new thief ants are on the way.

According to School of Ants, thief ants are distributed throughout the United States (although they don’t show any records for New York State on the map). I had never noticed thief ants when I looked for ant colonies in that location in the past. I know my vision hasn’t gotten any better, so that isn’t it. It seems like thief ants have gotten a lot more numerous there.

Have you noticed more colonies of thief ants where you study ants? Do you think this a trend or a random happenstance?


5 Replies to “Have Thief Ants Escaped?”

  1. Hey there! Thanks for the great photos! I am part of a team that has been assessing the diversity of ants in Manhattan (NYC) for a few years. Thief ants have actually been one of our most commonly encountered ants, especially in the medians of Broadway Avenue. Exactly where in NY were you looking?

  2. Hi Amy,

    This is smack dab in the middle of the Finger lakes region, near Cornell University.

    Interesting that they are so common in NYC.

  3. I don’t think they’re getting any commoner here in lower Midwest (the near-South), where they’ve been abundant throughout the several decades I’ve lived here. Maybe the climate getting warmer farther north has something to do with it.

  4. Quick question for Amy: I am working on some games for Ranger Rick magazine (National Wildlife Federation). Do the thief ants of NYC steal from pavement ants?

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