I have lived in my house since 2007. I have a large crawlspace (dirt floor, ranging in height) where I have a nice woodworking shop.
In 2011 the shop became infested with fleas, but not the upstairs. Two rounds of flea bombs got rid of them but they came back this year. There is no food or water source for them in the crawlspace.
I imagine that another round or two of flea bombs would get rid of them this time too. Is there any way of getting rid of them permanently? As there is no food or water source for them this seems doable, but I can't think of how.
Best Answer
The fleas are most likely lying dormant (deep) in the dirt floor, below where the bombs/sprays will get to.
Couple/few options:
Number 1 is most permanent, #2 is dangerous as all get-out (and probably illegal), whereas #3 is cheap and safe.
Diatomaceous earth is (basically) fossilized algae powder. You spread it on a surface and it will absorb fats out of the waxy outer protection on bugs like fleas, mites, etc. when they land on it or walk across it, dig through it, etc.
Once those fats are gone, the pest dehydrates and dies.
It'll take some time and effort applying and re-applying, but it's cheap at about $40-50 for a 50lbs bag of "Food Grade".
Doing an Internet search for "Diatomaceous earth" and "Fleas" and you'll finds lots of direction on using it for your application.