Carpenter ants are typical of most ant species.  Just killing the ants that you see in your house may not achieve too much.  The goal is to kill the queen ant back in the nest as she is the only one that can lay eggs.  The worker ants that you perhaps see in the house do not reproduce and when they are killed they are quickly replaced by new workers hatched back in the nest.  So the key to control is to kill the queen directly (by removing the nest) or indirectly by some pesticide (e.g., advion) that is carried back to the nest by the worker ants.

For some excellent information on carpenter ants, please see:

https://www.extension.umn.edu/garden/insects/find/carpenter-ants/

Most carpenter ants nest outside but the workers are capable of traveling for considerable distances.  Consequently, the ants that you are seeing may be coming in from outside.  This is very typical behavior for them during the spring.  Sometimes carpenter ants will nest inside, especially in moist areas.  Contrary to popular thought, carpenter ants do not eat wood but burrow through it during the establishment of their nests.  If you are finding small piles of sawdust inside the house (i.e. the base of walls), this would indicate that the nest is inside.  However, not finding such piles would not necessarily exclude the possibility of an indoor nest.

I am a bit puzzled by why you think that their nest is inside the wall.  How do you know this?  If it is indeed inside, then spraying something around the outside foundation of your house will not do much.

Carpenter ants like moist areas and food that are high in protein and carbohydrate.  If you can eliminate these two conditions, the ants will soon disappear.  They seem to have an innate sense as to where your kitchen might be.   Carpenter ants rarely nest in dry wood.  Indoor infestations can be tracked by points of entry such as attic vents, foundations, cracks, electric wires, pipes and telephone lines.  Carpenter ants prefer to nest in structural lumber such as in wall voids, hollow doors, windows and foam panels.  Carpenter ants typically seek wood that has been softened by moisture, decay or other insects.

 Again, my guess is that the primary colony of these ants is outside.  Do you have an outside woodpile next to your house.?  If so, then that is where I would guess that the primary nest is.  If such exists, remove the wood pile so that it is at least 100 feet away from the house.  In a more general sense, try to remove any wood or lumber that is close to your house.

It is not clear to me whether or not the ants that you have seen in your bedroom were before or after the pest person came in.  If it has been afterwards this further confirms my suspicion that these ants are coming in from the outside.

Good Luck!

 

Steve, thankyou for your response. The reason I feel the carpenter ants have a nest in the living room wall is because we started seeing the ants in the living room and in the bedroom directly above and in the basement directly below( and a few ants in every room in the basement) all at the same time in the middle of February on an unseasonably warm day but there was 2 feet of snow on the ground. My concern is that even though the pest control man put down advion ant gel bait that more ants will continue to come when the weather gets warmer. We do have colorado blue spruce trees and a pine tree in the back yard. If the ants appear again, what should we do?     Margaret

A quick question:

Is this the first time that you have seen these ants, or has this been a yearly occurrence?

Thanks

Steve, we have lived here for twenty years and never had any problems. We live in a residential neighborhood with a small backyard. The living room wall I am speaking of faces the backyard where the very large trees are close by.There is a large picture window in the living room with a wooden window sill that tends to look moist. We did see 4 or 5 ants last September on the dining area floor which is close to the living room wall I am concerened about.I put down a little Terro and that was the end of it,I thought. Our winter here in Minnesota has been exceptionally long and cold. I am looking at 1 foot of snow as we speak. Can the carpenter ants get in the house some how through all this cold and snow? And how can I protect my home if they swarm again when the weather gets warm? Our weather has been in the 30's.Thankyou, Margaret

Steve, I was just reminded that the very few ants that we saw in the dining area was in November of 2016 not 2017. Before a heavy snow storm.   Thankyou, Margaret

Thanks for the recent information.  And thank you for this interesting challenge.  Off and on over the past few days I have been giving your situation much thought.  Here are my current ideas:

1).  Just to be sure that you have carpenter ants, remember that the female workers (the ones you are seeing) should be between ¼ inch to ½ inch long.  Not that it really makes all that much difference – they are still ants.

2).  When one talks about a nest of ants, one is implying that a queen is present in it.  The queen can live for as long as 10 years and produces enormous numbers of eggs.  If indeed a nest (with a queen) was present in your house, I don’t think that you would have seen the sporadic appearances of ants that you have.  And related to this, ants are not coming into your house at this time of the years given the snow and the temperature.  The ants that you are now seeing are indeed living within your house.

3).  Ants can also establish “satellite” colonies both inside and outside.  Queens are not present in such colonies.  They are established by worker females when space/food are limited in the actual nest.

4).  What I now believe is that you have a satellite colony somewhere in your house.  Since the inhabitants of such a colony can live for as long as two years, this would explain why you still have ants now after a year and a half (2016).  The members of this colony can become dormant during cooler temperatures and then start to forage when temperatures rise.  This might explain why you started to see ants a few months ago.

5).  If a satellite colony exists in your house, no swarming will occur since there is no queen. 

6).  So the focus now is simply to get rid of the ants in the house.  Terro is an excellent product.  I would suggest that you use the small plastic trays as you can place these in many different places.  Last fall after I brought in my geraniums to over-winter, I started to experience ants in my house.  They came in with the geranium pots and soils.  I used this product and within three weeks, no more ants.

See:  https://www.target.com/p/terro-ant-killer-indoor-liquid-ant-baits-6-pack/-/A-15024212?ref=tgt_adv_XS000000&AFID=google_pla_df&CPNG=PLA_Patio+Garden+Shopping&adgroup=SC_Patio+Garden&LID=700000001170770pgs&network=g&device=c&location=9019403&gclid=EAIaIQobChMIxP7OmOO82gIVnrXACh0o2gOBEAQYASABEgK1evD_BwE&gclsrc=aw.ds

And with 2 feet of snow on the ground today, spring can never come too soon.

Best,

Thankyou for this information. it has been very helpful. Knowing the amount of time that the colony has been in the house, and knowing the pest control man put down advion ant gel which seems to be working so far, can you tell me how many ants these colonies produce? I have seen well over 100 dead ants so far and killed at least 30 myself, what can I expect in the weeks as the weather warms up? I am not seeing any activity right now so I am not sure if I should place the bait traps now or not.  Thankyou, Margaret

Margaret: 

it really is impossible to say how many total ants might be in the colony in your house.  It could be as few as a couple of hundred but also could be up in the thousands.  If, as I continue to suspect, that there is not a queen residing in your house, the ants are not reproducing and thus not increasing.  To eliminate them completely will just take time.  The fact that you are not now seeing ants is a good sign.  I would not put out any additional bait traps at this time.  Wait until ants appear again.  My feeling is that as time goes by, you will be seeing fewer and fewer ants.  In the meantime keep in mind that the reason that ants might be in your house is that they finding food.  The most powerful sense in an ant is their sense of smell.  They are most attuned to sweetness.  When I was experiencing my ant infestation last fall, I finally decided it was really my fault.  I enjoy my coke/pepsi at night while watching the news.  Often I would leave my glass or can next to the geraniums.  It was truly an ant-magnet.  I would come down in the morning and find hordes of ants around the glass/can.  So be sure that there are no open food containers in your kitchen.  Not wanting to be "preaching", but a clean kitchen is important to keep ants at bay.

Keep using the Terro,  I now think with patience this is the best option.

Best

Steve, thank you so much for your knowledge and suggestions. I am probably the only person in Minnesota that isn't wishing for spring to come. Do you think that when the carpenter ants became active in the home in mid February during that warm week we had, then pest control came and laid down the Advion gel bait, that they are now dormant in the wall because it got cold again? Or do you think that the advion gel bait could have killed them ? I guess I am wondering if our extremely unpredictable weather plays a role on whether the ants will become active again in the home? I am also wondering if when the snow melts I should place the Terro ant trays outside of that living room window on the ground?
Thankyou, Margaret

Margaret:

I would adopt a wait and see process.  Dormancy is not usually an "on-and-off"  process.  It is not something subject to daily temperature fluctuations. I continue to be of the mind that there was a colony of dormant ants in your house.  How many were in that colony is unknown.  Perhaps the pest control procedures killed them all.  This would be my guess.  I would not place any Terro traps out until and unless you see additional ants.  With any bit of luck, your ant problems may be behind you.

 

Steve, I had been feeling pretty good about not seeing any activity in three weeks until last night when I saw a single very large ant in my daughters bedroom upstairs across the hall from mine. I am hoping it is an isolated incident and hoping there isnt another colony in the wall on that side of the house. I am afraid to lay any terro bait in her room because it might draw more ants in there.Her room and window face north. How long would it take for a second colony to set up in that north wall if that is the case? I had seen a few ants (5 or 6) back in February in the den which is directly below her room and in the basement room (5 or 6) which is directly below the den. Pest control did lay down advion bait gel in the den and basement room below the den. Do you think I should lay down bait in my daughters room? Margaret

Margaret:

I would not be unduly concerned about this.  I really doubt that you are dealing with a new colony.  Remember that worker ants can live for over seven months.  My hunch is that what you saw was just a lingering ant.  It would not do any harm to put a Terro trap into your daughter's bedroom.  However unless there was some type of food in her bedroom, I think that it might have just been an ant =in search of food.  Getting rid of ants is an exercise of our patience.

Steve, That is interesting about the worker ants being able to live over seven months, with that being said do you suppose this colony was set up in the living room wall just this last fall 2017 and not 2016? What months do they try and get in to houses to build their satellite colony?

Margaret

Margaret:  Keep in mind that a satellite colony, by definition, is one that is lacking a queen but consists of a "gathering place", for lack of a better term, for ants who find that their home colony has insufficient food/space for them.  I am still of the mind that the ants in your house, at least in recent months, are coming from a satellite colony within your house.  This would be a colony that is once established becomes a place for outside ants to gather at various future times.  It more or less just persists.

So my best guess is at this time is that a satellite colony was established at some point in the past in your house (2015? 2016? 2017?) and this is a place to which new ants from the outside are continually attracted.  Obviously if this is all correct, this migration of new ants into your house has not occurred within the past winter months.  So any ants that you are now seeing reflect female workers that came in last fall or when ever.

So two suggestions:  Keep up the Terro treatments within your house.  Secondly, to really solve this problem will be to identify the ants' entry into your house and to locate the mother nest of these ants, which I believe would be outside.  For this latter, as you do your spring clean up, look for rotting, damp wood on your property, especially if it is located within 100 feet or so of your house.  If you are fortunate to discover a nest, completely destroy it.  With respect to entry, look for entry points along your foundation that are moist and close to the ground.  This may or may not be an easy task.

Good luck

Steve, once again,you are a wealth of information and I thank you. I was talking to my next door neighbor last night and she told me that they now have carpenter ants in their second floor bathroom which faces the east. Interesting because our problem started in the fall facing the west. When I first started seeing our ants mid February on that very warm 50 degree day, I had noticed a pest control truck across the street from my next door neighbor. We do have some new construction going on in our neighborhood, about one block away. About 20 new homes have gone up in the past 2 to 3 blocks. Do you think the removal of trees and brush when clearing out the land to build these new homes could have started up the carpenter ant activity here? Thanks, Margaret

Margaret;

You may have stumbled upon an answer to this puzzle.  Female carpenter workers have been known to travel over 100 yards (the length of a football field!!) in search of food.  When trees were removed in this construction, I suspect that many of the roots, but perhaps not all, were removed.  Carpenter ants just love decaying roots as they are typically moist.  So, just guessing now, if colonies (including queens) moved into these roots they would have found ideal conditions to grow and multiply,  Then if things got too crowded, satellite colonies might have been established else where such as in your house as well as the neightbor's.  But, these satellite colonies would have been established within your house only if food was present.  I would again go on a major spring cleaning in your kitchen, basement, cupboards,where ever to eliminate all spilled food.  Wipe things down completely around areas where you might have candy or any sugar containing food.  Don't worry about your refrigerator as it would be very unlikely that any ants would get in there.  Check out your daughter's bedroom.  Does she eat in there?  Have pop in there that might have been spilled.  What about your living room?  Do you entertain in there with food?  The fact that you are now finding only an isolated ant or so means that you are getting on top of things.

Finding ants in bathrooms is not unusual.  They love moist areas and that would be the first place that I would look at for the location of a satellite colony.

By doing these things, as well as putting out the Terro, I feel quite confident that your ant sightings will get fewer and fewer and eventually disappear.  Related to this, don't waste your money by calling in pest control people.  You can do everything yourself that they would do.

Keep up the good fight.

Steve, I have been reading over your past responses in search of answers. I am still seeing a few very large carpenter ants in my home. I usually see 2-4 each day. They are mostly by that wall in the living room where I feel the satellite colony is in the wall void and in the laundry room which is on the opposite side of the house in the basement. My question is, how long should I leave the terro ant gel bait /advion ant gel bait out in the living room, upstairs bedroom and laundry room? I want to be sure they are all out of the wall void and dead. Here is the problem. I had the pest control people out when this problem first started. They put down the advion ant gel bait in the living room, upstairs bedroom/bath and laundry room. I did some research and that product should last 2 weeks so I bought my own Advion gel bait and have been putting that down myself. The pest control man  put down termidor on the outside of the house the first of May. I called the pest control man 2 days ago to let him know I am still seeing a few ants in the home each day. He told me that the carpenter ants are everywhere this time of year and that a few ants in the home are normal. He also told me I should remove the ant gel bait on the inside of the house because this is like leaving food out and will attract the ants in to the house from the outside yard. But what about the carpenter ants that are still lingering in my walls? I am so confused! What do you think I should be doing now?      Margaret

Hi Margaret:

I think that your pest person gave you some good advice about putting Terro outside of your house.  Remember that these ants are attracted to moist areas.  Consequently I would continue to put out the Terro in your bathroom and laundry room.  My guess is that one or both of these rooms is closest to the actual ant colony.  Putting the Terro here should be the most effective.  Again I am of the belief that with the summer months, you will encounter fewer and fewer ants.

Good luck

Margaret:

As a follow-up to our discussion of a month or so back, I am curious as to the ant situation in your house.  Hopefully things have improved for the better.

Best,

Steve, Thankyou for following up. The carpenter ant situation inside the house is dwindling, finally! I have seen only 1 or 2 dead ants within the past 2 weeks, in the rooms connected to the infested wall void which unfortunately was in my bedroom. I have left the advion ant gel on the baseboards in my upstairs bedroom and bath. The pest control person told me I should be washing the baseboards near the carpet in the infested rooms to eliminate any pheromone trail. However, I am thinking that if I wash up ALL the advion ant gel bait there could still be some ants in the wall and then they won't die.What are your thoughts?

We did have the pest control person spray termidor on the perimeter of the house the first of May. I do see a few dead carpenter ants in some webs outside of the garage just above the garage door. My main concern is how to keep them out of the house and wall void when the weather starts to get cold again.

Steve, I forgot to mention that we still have some construction of more new homes about 1-2 blocks from our house. I have also heard other neighbors mention that they have experienced these carpenter ants in their homes, fences, patios. We do have a large screened in porch(cedar) on the back side of the house near where I believe the entry point to be. TThhe porch/deck is 17 years old and some of the wood is starting to rot. Do you think that the weathered cedar is what is attracting the carpenter ants to our home?
Thank-you, Margaret

Hi Margaret,

I am in the process of consulting with the U of M entomologist for his suggestions and advice.

Have been wondering whether or not your ant problem still exists.


Steve

Steve, Thank-you so much for consulting with Uof M for advice. I have only seen 2 dead carpenter ants in the house within the past 3 weeks. I am hoping that the ant gel bait that was laid on the baseboard  has lured the ants out of the wall and that they have either gone outside or have died. I worry about more eggs (and queen) being in that wall void. With the carpenter ants now being in our neighborhood what should I do to keep them from following their own pheromone trail back into the same wall void when the weather gets cold ? We have replaced most of the soft and rotted wood on our cedar deck in the backyard and plan to have the stairs replaced soon as that wood seems to be softening with age.We are strongly considering replacing the entire thing with maintenance free composite. Thanks again, Margaret

Margaret:

Below is the response that I received today from the University's entomologist:

On Tue, Jul 17, 2018 at 4:44 PM, Jeffrey Hahn <hahnx002@umn.edu> wrote:

"Hi Steve,

 It is common to see more carpenter ants at first after bait has been applied. That's good; that means they are loving the bait and taking it back to the nest. If they have any specific questions about what the technician has does, the resident should talk to the pest control company.

Spraying the perimeter of their house is not effective preventative. Here is the link to our fact sheet, https://extension.umn.edu/household-insects/carpenter-ants.

Jeff"

I have since written back to Jeff asking him how to distinguish between having a satellite colony in a 
house versus 
having a full-blown colony with a queen in a house.. It may be a week or so before I hear back from him.

Be sure to read the link that he provided.

Best, 
Steve

Steve, Thankyou for this information!! I am curious to know if Jeff knows anything about carpenter ants infesting entire neighborhoods at a time when new construction is near by and is the presence of the carpenter ants permanent for our neighborhood now or temporary? We have lived here in Eagan/ Inver Grove Heights(border) for 20 years without ever seeing these carpenter ants. I am also wondering what causes them to become more randomly prevalent and is this becoming more common in other parts of the Twin City area?    Thanks, Margaret

Margaret:  I have heard back from the U of MN entomologist.  He said that carpenter colonies within buildings are usually satellite colonies.  He suggested that you continue putting out the ant bait in your house.  He felt that in time this should eliminate any satellite colony within your house.  New construction per se would not favor the establishment of colonies by carpenter ants.  However if there is still wood debris still around the construction area, such debris should be removed.  If trees were removed during the construction, are the stumps still present?  This would be great habitat for carpenter ants.  I would expect that as the season rolls into fall, you will be seeing these ants ob a more infrequent basis  This would especially be true if you continue to use ant bait in the house.

Good Luck!!