Friday, January 09, 2009

What are these BIG black ants in my house?

big black carpenter ant
carpenter ant
In early spring or late winter people often encounter these large black ants in homes. These big ants are different than the more common small, brown "nuisance ants" that plague kitchens. The big ants are called carpenter ants (Camponotus spp.) and unlike their smaller cousins, nest above ground in cavities. Nest building and cavity expansion by these large, powerful ants can cause damage if nests occur in our homes.

Most of the ants you find in homes are small, less than 1/4", and brown. There are several species of small brown ants that can nest in our home's walls or nearby soil and enter homes in search of food and water (see House Ants for identification and control). Nuisance ants are just that, a nuisance. They won't damage your home and pose no health threat of any kind.

There's another ant, however, that occasionally is found in homes that is much bigger (1/4"-5/8"), darker in color, nests in the walls, floors and ceiling and can cause significant structural damage if not treated properly. People's first reaction often is "what are these BIG black ants in my home?" These are the carpenter ants and they can destroy the materials (structural wood, insulation, sheathing and so forth) that surround their nests. Thousands of dollars in home damage can be caused by a single carpenter ant nest as it grows.

Winged (left) and wingless (right) carpenter ants
Carpenter ants normally forage outside for food and water. Foraging ants will therefore move back and forth between their nest in a house and their hunting/foraging grounds outside. Carpenter ants are scavengers and predators taking whatever food they can find. The only time they normally enter the living space of homes is in late winter and early spring before their food sources develop outside. Therefore, if you find more than a few of these big black ants indoors, especially in spring, that's a pretty sure sign that you have a nest somewhere in the home. Don't be concerned about carpenter ants you find outdoors at any time of the year unless they are trailing into your home.

You may also find carpenter ants with wings (see photo above). These are the so called "reproductives" that start new colonies. Since this stage can easily shed their wings the ants you find indoors may have actually flown in through an open window or door.

Once you confirm the workings of a carpenter ant nest in your home (see Inspecting Homes For Carpenter Ants) plan to treat the whole house (see links below). There is no need for "periodic maintenance treatments" advocated by some pest control companies, treat only when you know for sure that there's a problem.

Use the following articles to treat carpenter ant nests around your home. If you are handy you can probably do most of this work yourself, except perhaps repair of existing damage. If you are not so handy take a look at the article below about hiring pest control services.

35 comments:

Karin said...

Is it usual to see carpenter ants around new construction? We're in our second year in this home, there were no signs last year, but now we've seen ants, in the front and back. Very wooded area out back, but not in front. Mulch is very low, and there is no soil near the siding. The slab is about 5" high all the way around.

Jack DeAngelis, Ph.D. said...

It is not unusual to see carpenter ants around new or old construction, and it is not necessarily reason for concern. This is especially true near a wooded area. Carpenter ants can be very common so you expect to see them outdoors. If, however, they are "trailing" between the house and the yard this can indicate that there may be a damaging nest indoors and control may be necessary. See the carpenter ant links above for more information.

wchuck said...

I live in central Mississippi. I have never seen these big black ants before, and have lived in this house for 27 years. Mostly I have seen them outside, but I left the garage door open for most of the day and early evening, and found them on the walls in the garage. When I turned on the outside lights and went out, they were all over the sidewalks and driveway. Should I be concerned about this, and what is appropriate treatment for these ants when they're outside? Thanks!

Jack DeAngelis, Ph.D. said...

My guess is you are seeing either a carpenter ant nest that is splitting (sometimes called budding) and moving, or the reproductive flight of a large nearby nest. This is not necessarily reason for concern as long as the nest is not located inside the structure.

Once this flight/migration has finished in a few days inspect around the house to see if ants are trailing to and from the house. If they are this means there's a nest in the house and needs to be treated. If not, the nest is likely located outside and does not not to be treated. See the Related Articles for more info.

Scott said...

We have started seeing carpenter ants at the same time we began installing porcelain floor tile in the basement. Are these related or not? We keep seeing the ants crawling across the tile as we are installing it, but can't determine their origin.

Jack DeAngelis, Ph.D. said...

I doubt that the tile installation and the ants are directly related. If you regularly see carpenter ants indoors it probably means there's a nest somewhere in the walls, or possibly subfloor. Check outside for ants trailing to and from the house (see links above). If you need to treat see the links for perimeter sprays and carpenter baits that can be used.

zahraa said...

true and bu the way they only come in groups and they become very big and large. They only come into your house if there is a nest somewere inside your house

Mike Amadori said...

We live on the second floor of 3-storey wood frame apartment building. It is our first spring here. Also, we just finished having the laminate flooring throughout the whole apartment redone as well as a section of drywall replaced (damage from a burst water pipe). We had exposed concrete and interior walls for about 2 months. The work finished last week and since then we have found 6-7 big black ants around the baseboards where most of the work was being done. I imagine most pesticides are not meant to be used indoors. What can/should I do if I am worried about a colony forming? Thanks!

Jack DeAngelis, Ph.D. said...

Mike,

Contact me at livingwithbugs@gmail.com and we can discuss this. The options are too involved to list here. Also, take a look at http://www.livingwithbugs.com/carpenter_ants.html for some background info.

Jack DeAngelis

Kirstin said...

A couple days ago, I found a few large black ants in my kitchen. Since the first few, I have vacuumed up 30 or more in my kitchen, and even have found a couple in the bathroom directly above my kitchen. I have been unable to find where they are coming from, but they just keep coming. I tried putting out my boric acid/strawberry jam bait that worked when I had a problem with small brown ants last year, but these ants are not remotely attracted to it. How can I determine if there is a carpenter ant nest in my house, and when do I determine if it is a large enough problem that requires a professional vs trying to treat it myself?

Jack said...

Kirstin,

This many ants probably means there's a nest in the walls or subfloor. You can control carpenter ants yourself but it can be a lot of work. Most people opt to hire a pest control company (there are suggestions on our site at http://www.livingwithbugs.com about hiring a PCO). Contact me at livingwithbugs@gmail.com if you want to discuss this.

Jack DeAngelis

mlada1033 said...

Our roof was reshingled this past week and around the 2nd day of noisy pounding etc. we noticed very large ants in the house (10-15) Is there a connection there? The roofer did not mention he saw any ants. We do have wood siding and alot of wood chips in our yard.

Jack DeAngelis, Ph.D. said...

mlada1033,

I think this is more than a coincidence and probably means there's a carpenter ant nest in the roof. Take a look at the carpenter ant control options I've post at our 'Bugs site or contact me at livingwithbugs@gmail.com if you want to discuss this further.

Jennifer said...

I live in a small apartment on the top floor of a 3 floor building, and I have found maybe 10 large black ants wandering the walls of my kitchen and living room. Should I tell Management we might have a carpenter nest? Should I just put out traps and hope for the best? I haven't been home for the last couple of days, so I haven't seen any. But I'm not sure if I should tell Management, or if I'm just freaking out for nothing.

Jack DeAngelis, Ph.D. said...

Jennifer,

If the ants are more than 3/8" they are very likely carpenter ants. Tell the management so they can have them treated. If you are concerned about pesticide exposure during treatment tell them this as well. If you live on the top floor the nest(s) is probably in the roof and the cause could be tree branches that have been allowed to touch the roof giving the ants an avenue on which to forage.

Contact me at livingwithbugs@gmail.com if you have questions.

Jackie said...

How many carpenter ants is okay to find in the house before you start looking for the nest? I have a room in the basement and have found myself surprised by a daily giant ant for a few days now.

Jack DeAngelis, Ph.D. said...

Jackie,

This time of the year you can't really set a number. It is better to look outside for ants trailing between the house and yard where they forage for food. See the articles cited above for details about inspecting for carpenter ants. Contact me at livingwithbugs@gmail.com if you have questions.

ES said...

Its extremely hot here (over 100 degrees) and we have carpenter ant killers in the yard (the ones that go into the ground and are changed by the pesticide company). I've killed three ants in the house (we live on the bottom floor of a duplex condo), 2 by the door and 1 in the center of the house. I've never seen the ants come in the house before because of the outside treatment... I'm wondering if the heat has something to do with this? Could it be the heat destroying the pesticide faster? Or the bugs wanting to come in because of the heat and lack of flowers outside?

Sandra said...

I recently noticed several of these black ants in newborn baby's room by the door, and in the corners of the room. I have also found them in the corners of our room. After reading the article I realize it is these ants I am seeing but it is not early spring or late winter. We are in August. I am concerned because I do not want to think these ants may be crawling up into his crib or o him!

Brian said...

I just finished moving into my new apartment here in South Texas, last week I came across a big black ant, doesn't look like the one in the photo above (no enlarged thorax, everything fits size wise), but still half an inch! I couldn't kill it with a napkin, but it was no match for my boot.

Then tonight I see another one outside my pantry. I figure they're scouts since I've only seen one at a time. But would these still be carpenter ants if they appear as regular black ants but just significantly larger and are there any concerns: biters, stingers?

Thanks, Brian

Zema said...

I have tried to post this three times....so if it eventually shows up three times, excuse my ineptness with blogs!

I just had my house treated for carpenter ants. Part of the house is a two story structure. The tech said there was no need to treat the second story as the ants travel down at night to their nests. He did finally treat one wall as I have seen quite a few ants come from that wall. Why wouldn't you treat all four walls upstairs like they did downstairs? Is this customary or is this just a story to get out of treating the upstairs?

Thank you, Zema

Hope said...

I have not had any issue with any kind of ant until yeaterday. when I came hoem from work all was fine. About an hour later I went outside and was pelted with flying carpenter ants. There was wingless carpenter ants teeming all over the ground. It was as if the ground was moving. I couldn't believe it. did the wind blow them in? I had left the door open for a minute or two at one point as I stepped outside again. Since then I have been finding ants in the house - all over. I turn around and there is another. I think it is quieting down now. Should I still be concerned? Do you think they have moved in??

Prava Blondynka said...

I live in a wooden townhouse building which has 5 levels, including the patio roof top. My unit is on levels 3-5.

I have started to see the carpenter ants coming in (two yesterday on level 4 and one today on level 3). Are they coming in from the roof? The rooftop patio has a wooden floor (like a deck) on top of a metal sheet.

I had some trees in wooden barrels but they all died over the winter. I thought they dried out because of snow and wind. Could the carpenter ants be eating them to die?

I have an exterminator coming in. Please, help me where to look for htem. I am terrified of them. They are 2.5 cm! The exterminator (Orkin) said it would take up to a year to get rid of them, probably over 4 or more visits.

Brittany Long said...

Okay so we started seeing these big black ants with like a hard body in the kitchen. And now there are like 30 of them alongside the walls; all dead. Why is it that they keep dying besides where the wall meets carpet? And how do I get rid of them?

louie luck said...

I recently bought a travel trailer-pre-0wned. A few days after I got it home, I started seeing "big black ants" running around everywhere. My dad seems to think they were already in the travel trailer, what do you think? Thank you! carmen

Unknown said...

The former tenant of this duplex had my side with wood mulch that is rotted and yucky. Just had my son and his girlfriend completely uproot everything in the flower beds outside which is next to the house and now am starting to see them inside in the kitchen under the window. So, I shut the window but know that won't keep them out. Since they are inside, could there be a nest in the wall or should I just assume the wood chips are attracting and after I get that all cleaned out and rocked they will go away?

Theresa Keeney said...

I found a large black ant that fits the Carpenter Ant description crawling up my front porch. Of course I killed it and haven't seen another yet (1day). However, my neighbor also found one in her yard. Would these be scavengers? We live in a sub division that is surrounded by dairies and farming. Should we be concerned if we only see one or two?

Mama Bird said...

It is June 20th and I live in the Greater Cincinnati area. I have small black ants, and big black ants in my home. Could my big ones be carpenter ants, even though it isn't really spring anymore? I have not seen any with with wings; just large black ants.

Laurie said...

Help! I have large black ants in kitchen and we found them on pastry that was wrapped in foil, I heard something scurrying around and opened it to about twenty of these big black ants. Its August and is it comman for carpentar ants to eat your sweets. Also, my son and husband was out digging up wood post that had all these big ants on the post, could they possibly brought some and if so can they grown into a large nest that quick? We do live in a cedar house surrounded by woods and cornfields. When we sprayed these ugly ants they went up to our wood ceiling and I am guessing they may be in there, or they came in that way. It was just shocking to see that many large black ants eating my sweets. Any advice you can give would be greatly appreciated
Thanks, Laurie Decker

Abhay Nadkarni said...

We moved into this single family 2 floor+finished basement house in Nov last year and the home inspector prior to the house sale had noticed couple of carpenter ants in the garage.

The previous owner did a treatment through a company Terminite and i do have a 1-year warranty.

A month or so ago, i did start noticing 1-2 ants a day and couple of days back when i came home in the evening, i must have flushed out 20-30 ants, the next day almost a 100 and yesterday about 30 odd.

All of these ants appear from nowhere in my kitchen and family room.
I did notice 1 odd ant total so far in the basement and maybe a couple on the 2nd floor so far.
I did notice a dead queen ant in one of the 2nd floor bedrooms.

I have arranged for a treatment again from the same company.

Could you advise what i need to tell them or insist upon? Does the whole house need to be treated?

Ashley Ford said...

So.. We had a new garage installed today and now we see inch long if not bigger (like OMG that;s a huge ant big) all around the house, crawling on the outside walls, seen a couple inside the house and seen them right a long the pavement connecting to our house.Do we likely have a problem with carpenter ants? I know we already have a regular ant problem, but these are new and hadn't showed up until after the how deal with a new garage door being put installed.

Kristen Brown said...

HELP, we just spotted a number of big black ants that started coming from under our baseboards in our dining room. I have killed over 40 now in the last few days and I am really worried. How do we get rid of ants if they are in our home and how costly will the treatment be?

Linda said...

Are the big blank ants that are on Peony Bushes the same as carpenter ants

Samantha Hawk said...

Can these bugs hurt you? Like bite or anything? I've seen several in my home and one just crawled on my bed where my 2 small children are sleeping.

worry wart said...

We came home and found a big black ant crawling across our carpet does that me there are many if we found one