How to treat your air vents for bugs

What do you do when you’re chasing a spider or a roach only to have it escape into an air vent? If you douse the opening with Raid or poof some boric acid dust into it guess what will be coming out in about 10 minutes when the air kicks on. That’s right, you’ll either have the smell of your aerosol and or any airborne pesticide particles floating around your living area and this sometimes can go on for days. This is not good and for obvious reasons you should ALWAYS avoid spraying anything into air vents or air returns.

I’m often asked to spray in air vents but my usual reply is; “Sure, I can do that and when I’m done can I spray in your fish tank?” Of course the answer is always NO and a look of puzzled concern always follows. I explain that both actions are about the same because I’m putting pesticide in a place where you cannot avoid breathing it and I have no control of where it goes. Just as your fish will surely take ill it would be no less irresponsible for me to treat your vents in this way.

Can vents be treated?

The short answer is yes but your options are sort of limited. The best way is to simply remove the vent and place a fold up glue trap inside the vent. Since roaches and spiders can easily walk around the trap there is no guarantee you’ll catch them and while baiting with a smear of peanut butter might entice the roach it will give your home that nice aroma of a 3 day old school lunch sack. Maybe you want to think about that. You could spray around the vent but drywall sucks up liquids and it’s doubtful any residual would be on the surface in enough of an amount to provide a lethal dose. Plus you still may get airborne chemicals when the heat or or a/c turns on. Some vents are vertical and it is difficult place a trap inside, for these types what I sometimes do is place wide strips of clear packing tape over the vent leaving thin slits (1/4 to 1/2 inch wide) so that the air can still come through but when the insect tries to crawl out to freedom he will get stuck and die. Packing tape is great because you can still see into the vent and it usually comes off cleanly whereas masking or duct tape won’t.

Can bugs live in vents & do they come in from them?

Almost all bugs are sensitive to air currents in one way or another and roaches will actually avoid the air from a fan. To much direct forced air will begin to dehydrate the bug and if they do spend some time in a vent it won’t be long before they start looking to get out. As far as spiders or bugs entering your living areas from the vents, it’s not likely unless you have a break or tear in one of the ducts. In one case I treated a home that had fleas only in a tub and not all the time. After being man looking into vent pestcemetery.compuzzled for awhile the a/c kicked in and I suddenly had fleas on my shoulders and head. The air vent above the tub was kicking them out every time the air went on and upon further inspection we found a birds nest in a large tear of the flexible air tubing in the attic. The nest was removed, attic treated, the duct fixed and the clear tape trick got the rest. What happens most concerning vents and pest entry is that the vent itself is not sealed tightly up to the ceiling. Critters in the attic follow the air current, see the light or detect food odors through the opening and the slip through right next to the vent. This gives the illusion that they are in the vent which is almost never the case. While I may dust into the void to block them I most often suggest sealing up the opening.

These same rules apply anytime you are using pesticides and would include car vents, box fans, window a/c units or anything that will return your spray back to you in an uncontrolled way. If you think creatively you can get around the use of residual sprays in these areas and still get rid of your pest. You just need to think outside the vent.

Get Free Email Updates!

Signup now and receive an email once I publish new content.

I will never give away, trade or sell your email address. You can unsubscribe at any time.

About The Bug Doctor

Jerry Schappert is a certified pest control operator and Associate Certified Entomologist with over two and a half decades of experience from birds to termites and everything in between. He started as a route technician and worked his way up to commercial/national accounts representative. Always learning in his craft he is familiar with rural pest services and big city control techniques. Jerry has owned and operated a successful pest control company since 1993 in Ocala,Florida. While his knowledge and practical application has benefitted his community Jerry wanted to impart his wisdom on a broader scale to help many more. was born from that idea in 2007 and has been well received. It is the goal of this site to inform you with his keen insights and safely guide you through your pest control treatment needs.
This entry was posted in Spraying around series. Bookmark the permalink.
  • ivy

    Our dryer vent and all air vents that’s on roof got clean out recently now every one getting bit by something the apartment complex says when you find out what it is they call in someone to spray what can it be

  • The Bug Doctor

    ivy–they are correct. It could be any number of things. The first step in pest control is to ID your pest. That way you can go ahead with a treatment that will work.

  • The Bug Doctor

    I see roaches, spiders etc. ‘go in’ vents a lot. It may be to escape or the darkness might look like safety. Under normal circumstances they won’t make a home out of it-nor are they coming from the duct.. Use the tape trick and you can usually catch the rogue vent trespasser.

  • Sara

    We just had a large male raccoon (covered in deer ticks) removed from our attic/crawl space. We recently noticed that the deer ticks were coming into our living space from the air vents and returns above. We have pets, children and pregnant people staying in the house and can’t do aggressive pesticides. We have a virtual infestation of Lyme ticks in our home — like a horror film. Any suggestions? We need help ASAP.

  • The Bug Doctor

    Wow that’s terrible. I’m not sure there are any ‘home remedies’ that would help besides being vigilant with a vacuum cleaner with hose attachment and perhaps some alcohol in a sprits bottle. But it sounds like you need way more. If they are coming out of the vents and or around them I think the tape trick may help catch a few. But honestly I think I’d call in a pro and see if they can’t make short work of it. The fear of ticks crawling all over the place to me is far worse than some well placed pest control products.

  • Rebecca

    Just recently we have started having a problem with fleas in one of our bathrooms. I have been vacuuming every day, sometimes twice a day and I have sprayed bug spray that says it kills fleas but nothing is working. Within a day they are back and they do not seem to be infesting the rest of the house, just this bathroom. We can’t figure out how this happened or why we can’t stop it so far. Our cat is treated every 30 days for fleas and she does not go outside and does not even go in that bathroom, she hangs out mostly in our downstairs or in our master bedroom and bath. She even sleeps with us and there are no fleas biting us in bed or around the rest of the house. We are about to try the flea bomb because the spray I’m using doesn’t kill the eggs so I figure this is why I can’t get rid of them but I just want to know why only that bathroom and how? Oh and the whole house including that bathroom is tile and hard wood there are no carpets. What could be the reason for this.

  • The Bug Doctor

    most likely not fleas–or that’s my guess by what you’ve described. I’d be inclined to say you have springtails as this is a common story line…

  • Alex

    Hi! Great article. Thanks for it. I have a question for you about silverfish. I just moved into a new apartment, the building’s not that old, built in 2007 and it never occurred to me I’d have a problem. I found lots of the little critters in the kitchen, the laundry room and the bathroom. I used boric acid and spread it along the baseboards and in the bottoms of lower cupboards. Seems to have brought everything pretty much under control, except I’m puzzled about the bathroom. I had a week of not seeing any and then suddenly I found four of them, seemed very healthy, not impacted by the boric acid at all. They were also in the middle of the bathroom floor. I put a glass to cover the drain in the shower and closed the drain in the sink at night, and again I found more. The only thing I can can think is that they are coming out of the vent in the ceiling. There isn’t a fan in it, at least not one that I can control, but it’s there to allow the steam out of the room. Will your tape trick work for silverfish? I know they can squeeze through very small openings, and don’t they also see tape as food? Won’t I be attracting even more? Thanks so much for your help.

  • The Bug Doctor

    The attic is most likely where they’re at. Sounds like that vent may just end up inside the attic since there is no fan. If you can screen the other end that may help. The tape won’t attract them and should work btw.

  • Christine

    Lately every 1 to 2 weeks I feel find at least 15 to 20 baby spiders around our stove. Do u think they are coming from the air vent to the fan above it?

  • Brionna Lashea

    HI, I live in a 4 story apartment complex. I live on the third floor. I’ve lived here for a few months now and I had to have the apartment sprayed when I first moved in. I thought the bugs were gone, but in the past week, I’ve seen a roach in my bathroom, and one climbed out of the air vent in my bedroom. I haven’t seen them any other place in the house. I say roaches because that’s what they look like, but I could be wrong, they may be water bugs but either way how would I get rid of them before it becomes a problem. I’m not a dirty person at all, is it possible that there is an issue in another apartment?

  • The Bug Doctor

    Apartments are a ‘shared’ problem situation in many cases. You share common walls, plumbing, electric wires using same space etc. I’d consider having regular service. Most complexes already offer this so you might want to check with mgt.

  • Nonni

    I live in an apartment that has huge issues with yellow
    jackets coming in. I bought some foam at
    a fabric store and cut it in strips and pushed it down between the carpeting
    and the baseboard to at least trap them from just walking in. I had secured window screening with duct tape
    inside all of my heat registers and cold air returns, but over time I noticed
    that the duct tape loosens. Also, you
    cannot really clean the screening very well and it should be cleaned every year
    in the cold air returns because the dust collects on your screens and can block
    air flow. You will be amazed how clean
    your furnace filters will be when you have screening on your cold air
    returns. Now that the screening is
    coming loose I decided to buy some of that white netting that is sold for
    bridal veils in the fabric store. It is
    very stiff and you can buy it with holes that are the same size as metal
    screening. The downside is that tape
    resists sticking to it. I got around
    this problem by putting two way sticky tape on the outside of my vents first,
    pressing the material down on top of the tape and then running a bead of
    Elmer’s glue on top of the material where it joined the sticky tape. Applying the netting to the outside of the register
    makes it easier to vacuum the netting material.
    Just because your cold air returns on the floor are covered with screen
    or netting, this doesn’t mean that the bugs can’t get in. They can still come in if you have any space
    around the cold air return, including the space on the bottom hidden by
    carpeting. This is why it is important
    to use the foam strips to press between the carpeting and the baseboards. Also, when dealing with bugs check all
    around your windows for spaces, cover any bathroom fan vents or fan vent over
    the stove with netting. There is also a
    rope caulk weatherstrip sold in hardware stores that never dries out and can be
    pressed into cracks. And just ordinary packaging
    tape, duct tape or even masking tape can be your first line of defense when it
    comes to bugs.

  • The Bug Doctor

    You covered a lot there…Thx.

  • Nonni

    I just wanted to revise my previous post about applying the
    white netting to my heat registers. I
    noticed that it says on the Elmer’s glue bottle that it doesn’t work well if used
    where it will be exposed to heat. So I
    bought some white Duct tape and after first putting the two way sticky tape
    down and then my netting, I covered both with a strip of the white Duct
    tape. This managed to stick to the
    tape-resistant netting really well and has a better grip than the glue.

  • Mar

    Just moved to a new room and I’ve having a problem with house centipedes. Usually about an inch in length and light brown color plus a few black ones. I find 4 or 5 a week and now I am finding baby ones. Our apt is on the 3rd floor of a 3 story building. And I have 3 vents in my room. What can I put over the vents so that the thin and tiny centipedes cannot come through? I have filled all gaps along floorboard with caulk. Could it be the window? What other steps can I take to secure my room?

  • The Bug Doctor

    window screen would work and be discreet. Caulk is your best friend for the rest–especially the plumbing areas which are lead ways from one unit to the other.

  • Nonni

    There is very fine netting available to prevent an insect called noseeum from getting into the home. Not sure if a tiny centipede is smaller than one of these insects or whether enough air could come through your vents if you used this. Just Google noseeums or try this link which I found interesting about just using bridal veil material on boats. Noseeum window screening is available at some sites as well.

    Also, thank you Bug Doctor for a very helpful website!

  • The Bug Doctor

    That’s a pretty slick idea… that material is pretty tightly put together…Thx.

  • Gaby

    I have three inverter ac installed in my house(one in the living room , and one in each of the two bedrooms), with the outside part of the unit installed on the roof of the house. Huge outside roaches keep getting in the part of the unit thats inside the house. Today I found one half dead on the floor of one of the bedrooms, it must have been blown out at some point, and another one alive and happy on the wall of another bedroom. And just now my husband went into one of the rooms and found two around the room before checking the ac unit and finding three more. It’s a nightmare, we never had roach problems before installing the inverters. They’re most likely coming in through the part of the unit that’s on the roof. What can I do?

  • The Bug Doctor

    If you can treat the attic with a bait where the lines run that would be good. Niban granular bait would work well. Then, or maybe even 1st…. Seal up any openings where the new lines come in.

  • Tasha

    Hello, I’m having the same issue. I’ve had our condo association pest control company come out now 4 times and I still woke up this morning to find a live roach in the upper corner near my bathroom ceiling. I’ve sealed up every hole and even covered all of the drains and overflow drains. The bug clearly had not walked through any of the poison sprayed along the baseboards. I believe they are coming from above–meaning an air vent. The pest control guy says this is pretty much impossible and they may be coming from the circulation fan in the bathroom. I’m at my wit’s end! I can’t sleep because I feel like a whole army of them is going to crawl out of the vents up above. Anything you can think of to do differently? I am on the first floor of a three story condo.

  • The Bug Doctor

    Try putting a strip or two of packing tape over the vent..don’t block the whole vent. You may not catch the entire roach but perhaps a dropping or part of a leg or something that gets stuck…This way you should be able to confirm this as the entry point.

  • Amy

    I have giant flies in my house. I believe that they are in the air ducts somehow because i find them in my house when I turn the heater on. Please help.

  • The Bug Doctor

    Amy. No worries. Your giant flies are most likely Clyster flies and are coming out with the heat and probably not inside vents but around frame of it. Vacuuming will rid you of them. No spray needed nor is it worth it. They are over wintering in the wall for the winter much like lady bugs do. In warmer weather. Go to south side of home and start caulking and sealing. That’ll work wonders.

  • Amy

    So where do I vacuum?

  • The Bug Doctor

    The dead ones and any live you can with hose attachment. They are slow and lumbering so it’ll be easier than a house fly. Cluster flies are harmless.

  • muna

    I’ve never had bedbugs and now moving into this apartment I do. The company hired a pest control and they did the heat treatment and put chemicals where the two apartments meet crevices and now I have found two live ones after almost 3 months later what should I tell them to do next pls help. I never want to see them again can’t sleep can’t eat I’m worried sick because I have young children.

  • The Bug Doctor

    I wouldn’t fret… simply call the mgt. or bug company back. Regardless of the method, bed bugs often require more than one treatment.

  • Elizabeth

    I recently moved in log home and have lady bugs, elder bugs and cluster flies that started in Sept, but are still in the house through the winter. I have been vacuuming like crazy, and sealing windows etc., any other suggestions? Are they just hiding in the walls and reproducing?

  • The Bug Doctor

    Keep vacuuming but in the spring, seal up the exterior. Especially the south side of the home.

  • Chad Schmitz

    Okay…need help. I am in an apartment complex. A few months ago an idiot brought in used roach infested furniture. My problem is that in the wall of my living room area there is a “return air vent” that is basically a hole in the wall with vent covers. It is about 12″ x 36″ and I was told it was required for air flow. On the other side there is one of the storage locker areas that has a water heater in it. This is the only apartment I have had with this type of “vent.” I need to know what can be done to keep the roaches from coming through that vent (which is basically on the floor level). I also need to know if it is truly functionally necessary. I don’t run my heat or AC much because the temp maintains in my small apartment and I use a fan for cool air for the most part. The roaches apparently just went into like a hibernation and during the first phase of infestation I had one in my bed crawling on my arm while I was sleeping. I am desperate and need a definitive solution.