You are here:

Pest Control/Large black ants in house in winter



We moved in to our house in the northeast (upstate NY) two years ago. I don't recall seeing ants the first spring we moved in, but this past spring we had quite a few larger black ants that I believe are carpenter ants. We were unable to figure out if they were coming in or going out but seemed to be traveling between the two. We attempted to poison them with gel and also sprayed around the foundation outside and at the base of the ceiling in basement.
Now this winter, during some of the coldest days so far,(under 0) I have seen them again to appear to be traveling from inside to out or the other way. We have a threshold that I believe is rotting and the ants go from that doorway to a closet area close to it. There is a crack in the wood flooring I believe they go down into. I have also found them farther away. The thing is, this area is still quite cold and I believe they are freezing to death. We keep our house at 57 much of the time and that area is even colder due to bad drafts, especially down at the floor from the crack under the door.
Mostly I am finding dead ants or those struggling to move.
I am not sure what to do. It seems like they aren't even making it back to their home once they venture out so I don't know if I should try poison, or just hope they all leave their nest and die.
I would love advice on what to do now and what to do come spring. I really don't want them living in my house.
Thank you for your help!

Dear Patti,

Does sound like carpenter ants for sure. They, among all the ants, are able to survive cold weather much better due to their ability to produce a kind of "anti freeze" within their bodies.

Poison baits are an effective way to deal with ants - but the trick is to get enough poison carried back to the nest to eventually kill the queen. I'm not certain if the following product is legal for you to use in New York, but you need to find out by calling a pest control company and asking them if they can use a product called "Termidor".

If so, have them come out in the spring and treat the exterior with that product. If not legal, then seek their advice on a solution. It may simply be a matter of replacing rotten wood on the exterior of your home, or it may require drilling and treating inside the exterior walls of your home.

Hope this helps a bit,


Pest Control

All Answers

Answers by Expert:

Ask Experts


George E Serdes


My knowledge is in the areas of structural insect or rodent pest problems. I do not know enough about lawn and garden pests to be of any help there...


I've retired from the pest control industry in Central Florida. I spent 15 years in all areas of the industry (sales, night technician, integrated pest management specialist, service manager, and branch manager for both National and local companies.

Formerly sat on the Florida Pest Management Association's Board of Directors (Region IV)

Retired Florida State Certified Pest Control Operator -

©2016 All rights reserved.