Mosquitoes through the fan vents


  #1  
Old 06-30-04, 09:26 AM
KNICKS33
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Mosquitoes through the fan vents

Stop me if you've heard this one before -- my two upstairs bathrooms have been taken over by mosquitoes and midgies that I thought were coming from the AC -- the folks on the AC board set me straight. They're coming from the vent fans, which vent into an attic crawl space that has nothing in it but a light and the AC. I came from a house with no central AC, no fan vents and a walk up attic (I've been here less than a year) so this is new to me, and I can't climb so I can't negotiate the ladder up to the crawl space or even lift the board to get into it -- I've only seen it by looking up when the home inspector did his thing, and the AC guy came for the beginning of the season. There are no windows in there, and I can't guess how they're getting in, but right now, I'd just like to keep them out of the living space -- I can't imagine they could do damage in the crawl space. I'm very leery of pesticides, and I don't really want to call an exterminator for a number of reasons, but is there anything anyone can think of to keep them from coming through the vents? The idea of spraying something toxic into something that circulates air isn't appealing. Is there a natural mosquito repellant other than the kind made for skin? So far, I've been lucky with killing them, but if they get into the bedroom, I'm cooked, it's a cathedral ceiling and I'd have to get a fire hose to kill them! Thanks for any help...
 
  #2  
Old 06-30-04, 02:17 PM
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Knicks, I'm not sure how or why you are getting mosquitoes in your attic. There should be nothing up there to encourage them, thats for sure. You mentioned a light up there - is this light on much? Many insects are attracted to lights, therefore it should be off as much as possible.

Also, is there any way you can get a screen on the vent fan. This could prove worthy of keeping insects from coming through the fan.

You could also do a walk around the exterior of your home and check for gaps and cracks that insects may be coming in through. I've heard over and over, th best pest control is exclusion. Meaning you shouldn't get much problems if insects have no way inside.

Other mosquito control methods include eliminating any standing or stagnant water around the outside of the home (old tires, bird baths, wheelbarrows, the list is endless). Mosquitoes love to lay eggs in wet areas, so the less wet areas - the better.

Good luck,

Jay
 
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Old 06-30-04, 11:55 PM
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Mosquitoes in attic

You state, "They're coming from the vent fans, which vent into an attic crawl space that has nothing in it but a light and the AC." Vents should never vent into an attic. You are moving moisture and humidity out of your bathrooms into the attic where you are creating a moist environment if vents are vented into attic area. If your air conditioner unit is producing a lot of humidity (uninsulated ducts or stopped up drain or other problems) then you are creating a moist environment which mosquitoes need to breed.

Mosquito larvae must live in still water for 5 or more days to complete their growth before changing into adult biting mosquitoes capable of transmitting disease. If you have standing water in the attic breeding mosquitos, you need to also inspect for mold, mildew, and rot. Inspect the attic ceiling for signs of leaks. Make sure attic is adequately ventilated. If you have soffit vents, make sure that they are clear of insulation so that the area is well-ventilated. Make sure that all possible entries for any insect or animal pest is well sealed to assure exclusion, which is the best pest control measure.

Removing sources of standing water around homes can significantly reduce mosquitoes in an area. With all the news of West Nile Virus, it is important that you investigate and make corrective measures to eliminate the mosquito infestation. Have your AC inspected for problems. Make sure vents are vented up through the attic and to the outdoors. Take extra steps around your home to make sure there are no areas with stagnant water such as in bird baths, pet bowls, wading pools, etc. Make sure gutters are clear and draining and there is nothing on the property where there is standing or stagnant water, such as in hollow stumps, garden ornaments, pool covers, flower pot saucers, etc. Do not allow water to collect in trash cans or other containers outdoors. Discarded tires are frequently mentioned in the news as breeding grounds for mosquitos. Remember, mosquitos need calm, standing water to breed. If you have an ornamental pond in your landscape, stock with fish to eat mosquito larvae. If you have a swimming pool that is not being used, clean and chlorinate to eliminate larvae. Make sure your lawn is landscaped in such a way that all excess water is carried away from the structure and there are no puddles anywhere. Check outdoor faucets to make sure they are not leaking and creating pools of standing water. Make sure all drains and ditches are cleared of weeds, leaves, and debris and that they are dug out in order to allow water to flow and not remain standing to create areas of stagnant water. Keep all flower beds and shrubs in order and trimmed to prevent hiding places for mosquitos.

Again, an inspection of the property and corrective measures should be taken to eliminate moisture problems and stagnant water that may breed mosquitoes. Eliminate all entries for pests. Spraying a pesticide in vents, as you say, would not be a healthy choice and would not address the source of the problem.
 
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Old 07-01-04, 06:26 AM
KNICKS33
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Thank you both for your help; I'm afraid the answer is, I'm toast! Allow me to have a small breakdown. I did buy a birdbath that I change the water in daily because if I wouldn't want to bathe in it or drink it, I figure the birds won't want to either, but that is the only standing water on the property -- the property is well-maintained, but the trouble is, I live in an area where mosquitoes are the State Bird. I'm also only a couple of miles away from swamps, and it's been a rainy spring, so my best answer is to figure out how they're getting into the house.

This is where the breakdown comes in. I blew $400 on a home inspector last summer before buying the place, and I've been uncovering things that he should have found little by little as I've lived here, and it has cost me a bundle. The inspection was last August, so he should have seen the mosquito problem, he has no excuse, AGAIN. I also had an AC guy out here in May to inspect the system, including the crawl space. He said nothing about any water problems or problems with the system. This house had to receive a CO from the town before the closing, and it did, and then after I had moved in, this little Napoleon of an electrical inspector came in and tried to create a huge problem for me, which only became resolved after much hassle and angst, courtesy of my lawyer and the local utility. This house was gutted in '99, and remodeled, and passed inspection then as well. I've heard about fan vents not venting into the attic, but like I said, I can't get up to the crawl space myself, so I'm not sure exactly what the set up is. No matter how well you think you've crossed the ts and dotted the i's, it doesn't work. Who can I trust to come in here and do the inspection needed to solve this problem? I don't even know where to look. Both people I had in here were recommended to me, so I have no faith in referrals, either.

I'm out of money and out of ideas, and am so leery of having people in here after all this that I have to stop myself from sneering at the UPS guy! If you have any ideas of the type of person I should call for an inspection, please let me know, but I thank you both again for your help.
 
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Old 07-01-04, 06:45 AM
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KNICKS33,

You say in your first post that the mosquitos are coming from the vent fans.
Have you actually watched them come out of there?
Also, you say that the vent fans vent into the attic.
Has someone gone up and actually checked or could they be connected to an outlet on the roof or in the eve?
It is possible that if connected to a roof or eve outlet, that there is no backdraft damper or it is stuck open.
 
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Old 07-01-04, 08:11 AM
KNICKS33
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Greg, it's a matter of deduction; it started in the master bath, which has one window that has never been opened because it doesn't have a screen. The window is completely secure. There were a bunch of like midgies and mosquitoes, and I assumed they were coming from the AC, because the problem started it seemed after I started using the AC. I know nothing about it, so I asked over on the AC board before calling my AC guy so I wouldn't seize yet another opportunity to make a jerk out of myself, and people there said, no, can't be the AC, then Ed said, what about the fan vents. A-ha! The problem is less, but present, in the guest bath as well -- they are back to back and, crossing the wall, the fan vents must be about within six feet of one another. There is a fan vent in the downstairs powder room as well, but no problem there. Don't ask me where that vents to. See, the thing that galls me is that, between the home inspector, the AC guy and the town inspector, someone should have said something if these things were improperly installed. And it makes me wonder how the former owner coped with these things for four years, although a lot of what she apparently did here makes me wonder. I can't believe all this stuff started up just because I showed up!

Who would I call to check on the potential problems you mention? I'm perfectly willing to memorize everything you suggest so that I sound like I know what I'm talking about, might lessen my chances of getting screwed over AGAIN! To tell you the truth, having come from a home with no fans in the bathrooms, I almost never turn them on -- I wish they weren't even there! Like I said, I can't go up to the crawlspace myself to check, so I have to depend on others, not an enviable prospect in this day and age, and totally against my character. But I'm stuck. I really appreciate your help, thanks!
 
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Old 07-15-04, 08:33 PM
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Mosquitoes

Anyone you know who has the physical ability to climb into the attic can look to see if the vent pipes exist and go up through the ceiling or outdoors. Or, perhaps a call to the person who inspected your home may recall what what was going on in your attic.

Are you sure that the pests are mosquitoes and not drain flies? These guys are black and triangular in shape and breed in sewers, drains, and traps. Fungus gnats also can breed in drains. If in doubt, capture some of the pests in a plastic baggie and take to your local Dept. of Agriculture Extension Agent for identification.
 
 

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