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.

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. Pestcemetery.com 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.
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  • PJ

    Hi, We moved into a home in Northern Virginia just 11 months ago. We have had an infestation of something or other for nearly eight months now. We had an air duct in the attic that was separated from the trunk line and when we had a duct cleaning company come to clean vents, they must have disconnected some more vents in the attic. That, plus we have a dog who likes to be outside and ended up with Lyme’s Disease from ticks. After the duct cleaning we noticed dirt blowing out of our vents. We wonder if this started the infestation. Didn’t know there was a duct separation until we had a new HVAC system put in and the technician saw it and sealed it.
    Since then we’ve had a new roof, a total attic clean out with new insulation and we are still having problems. We are at our wits end. We have an exterminator coming and still a problem What are we to do?

  • First step is to ID the problem..you made the right call getting a qualified person to come out to either find out what it is or rule out any type of pest… Once you know–THEN you can move forward with what to do

  • Scott

    I’m having the same issue, but I don’t have it anywhere else. I put up fly lights and Fly paper to trick and catch one of these, but I can’t see to get it. And as noted above, the Pest Control Professionals won’t apply anything because they can’t see anything.

    I’ll spray and aresoal for flying bugs and get relief for 2-3 days, before they come back. I’ve washed everything in hot soapy water and dried on hot hot heat. How can I get rid of these bugs?

  • Mariestallings

    Help! My 15 yr old daughter has not been able to sleep in her room due to the ridiculous spiders that have decided to come out at night! We live in Los Angeles and it has been over 100 degrees here lately. They are medium size black spiders and some are thin brown spiders. They are on her walls and the problem might be the water bottles from her guinea pig cages. ( I read your article about spiders being attracted to water. ) or the aloe Vera plant? But I just bought brand new miracle gro and I know there were no spiders in the bag. She has two other plants and I replanted those the same day too. I doubt it’s the plants but your the expert. what can we do? We keep only dry food in the GP cage and we feed lettuce during the day and it’s all finished, nothing left in the cage. What can I do? Also, the hallway right outside her room has an attic entrance. It looks like the sealing has a tight fit with the opening but I think spiders could squeeze through. Please give me any other solutions, this has become a nightmare. She finds 3-5 each night. I use peppermint oil and I doubled the amount of the oil, pls tell me what I am doing wrong.

  • Theresa

    I recently have discovered roaches since I have acquired neighbors with numerous cats. I have a house that is over 100+ years old. My air vents are on the floor. I noticed a roach going into the air vent the other day. How can I ensure that while treating the house for roaches that I am not overlooking the ventilation system? Since the vents are on the floor is there something I should be doing? I had an exterminator out several weeks ago, but he only treated my kitchen. Now I see them everywhere and I think the problem is bigger than I originally thought. I need help. My house is clean and after 4 years of living here I have never had roaches and now I don’t even want to come home! What do I do???

  • Linda

    It’s been four years now battling springtails. Unfortunately I am sensitive to them and they have plaqued me everywhere. We’ve had our home treated inside and out for over three years, but if I don’t vacuum and wipe the floors every other day, I suffer. We’ve caulked around the house, sprayed insulation on the cellar ceiling, epoxied the floor of the garage. You name it and I still notice them upstairs. Here’s my question. Could they be coming in from the ceiling heating/AC vents?
    The downstairs is a tough call because we bring them in from outside, but upstairs we don’t even bring our clothes is the bedroom unless they are just out of the wash. It’s been hell dealing with them. When they spring off of me I react like I’ve been bitten due to my allergies. I’ve lost countless night’s sleep. Im up for any and all suggestions.

  • Michael Hatch

    I’ve been having multiple insect issues in my 3rd floor apartment, which my landlords insist are simply because I live in a district of the city surrounded by garbage cans and restaurants. In short, their reaction was “deal with it.”

    I frequently find house flies buzzing around, but eventually they just drop dead on one
    of the windowsills. I sprayed the windowsills with bug barrier liquid, but that was months ago, now. It’s the oddest thing, like sometimes I’ll see them on the windowsill, squirming around and actively dying. I also find tiny mosquito-looking bugs on top of my air conditioners, also dead.

    The one that grosses me out the most, though, Is the bathroom. I find dead gnats all over my bathroom floor, every morning. I see the occasional live one buzzing elsewhere around the apartment. I know they’re bugs, and bugs happen, but I should not be sweeping them up every morning.

    Again, my landlords’ reaction was essentially “deal with it.”

    What can I do?

  • Get the critters ID’d first then that may give you a clue to a fix

  • I doubt highly you’re “brining them in” not in any great numbers if any….. Have you had them positively ID’d?

  • Linda

    Yes, by an exterminator. Our home is in a very rural area. It had been empty for a couple of years. When we tore the carpets up we found nests. Since I’ve written the last post, I put a filter over the vents and found almost nothing but I find them on the window sills. We truly were infested. We had the exterminator (several) spray indoors with Telstar inside and out but it was affecting me and my husband. We stopped and I now wash my floors( no more carpeting) with a solution of vinegar/water and Dawn dishwashing liquid. It helped greatly. The amounts I find now are mostly in the basement and damper areas.
    If I didn’t have such a sensitivity I probably would barely notice. It’s only happened since I moved here five years ago. Believe me, to someone with allergies, it’s an awful trial.
    Thank you for your answer!

    Linda