It sounds like you found success, but just leaving this comment here for the future. I’ve had some success this summer with Wondercide. (I am usually very wary of “natural” remedies.) I’ve been using their outdoor treatment and a camping fan and it’s making my backyard tolerable. (Mosquitoes love me.)

You can try sprinkling some mosquito bits in the stairwell and drain to prevent them in the future

Anonymous wrote:OP here -- thank you all for the suggestions! I don't think a single mosquito entered the premises!

I turned on the thermocell about an hour before opening the door. When it was time for the contractor to go in and out, I left a humble fan facing out. It worked with great success.

A couple days later, the mosquitos are back in full force in the stairwell, but as long as they're outside, I can live with it.

This is the most helpful, nicest forum on dcum.

OP here -- thank you all for the suggestions! I don't think a single mosquito entered the premises!

I turned on the thermocell about an hour before opening the door. When it was time for the contractor to go in and out, I left a humble fan facing out. It worked with great success.

A couple days later, the mosquitos are back in full force in the stairwell, but as long as they're outside, I can live with it.

There is this stuff from bonide with garlic and lemongrass or something that works well at keeping them away temporarily in the yard- I forget what it’s called but I’m sure Amazon has it.

Do the fan. On high right in front of the door blowing out. If it doesn’t work well in the first day, I’d misquote bomb it and use the fan.

how about hanging a temporary screen thingy? wouldn't be perfect but moderately effective?

Anonymous wrote:Thanks for the response!

I have a thermocell - it keeps the mosquitos from biting me, but the still seem to float around in a cloud of confusion.

Should I point the fan at the door from the inside?

What if I sprayed the exterior walls/stairs/doorway with OFF? would that help?

Just point the fan at the door, that will definitely work. Like blowing out the door.

Anonymous wrote:Thanks for the response!

I have a thermocell - it keeps the mosquitos from biting me, but the still seem to float around in a cloud of confusion.

Should I point the fan at the door from the inside?

What if I sprayed the exterior walls/stairs/doorway with OFF? would that help?

You would be better off doing one of the foggers right before the work is done. These are cans of spray that you buy at the hardware store. You pull the tab and it fogs the area with pesticide and should keep it clear for a few hours. That plus a fan pointed out the door should do the trick.

Thanks for the response!

I have a thermocell - it keeps the mosquitos from biting me, but the still seem to float around in a cloud of confusion.

Should I point the fan at the door from the inside?

What if I sprayed the exterior walls/stairs/doorway with OFF? would that help?

Anonymous wrote:A fan. Set up a fan, point it at the door, and just leave it on while he's there.

+1 they are very weak fliers

You could also do a thermacell, which creates a local cloud of permethrin.

A fan. Set up a fan, point it at the door, and just leave it on while he's there.

I'm having a contractor do some work - they will need to access outside, and inside. The access point is a walk-up basement stairwell where mosquitos LOVE to live, despite my efforts to get rid of any standing water or excess dampness. He will be using the door to go in/out in that stairwell, and I don't want throngs of mosquitos to come inside.

Is there any way to get them to temporarily abandon that nook for at least a few hours while the door is open?