Of course this question is more in the realm of green living than green building.
So I am answering as a green homeowner, rather than an interior designer.
- I believe that the bug would have to be directly hit with the tea tree oil to be killed.
- I have heard of using tea tree oil on lice, but it would be applied directly to the nits.It would be pretty hard to get the individual roaches directly.
If you are looking for natural pest control, I recommend that you use DE (diotomaceous earth) in crevices and inaccessible areas, and an orange oil pest spray on surfaces.
DE can be an irritant if breathed, so wear protection to avoid inhalation of dust.
Also, try to block insects' access to your home with caulk in any cracks leading to the outdoors, or into your walls.
- This includes cracks at the back of drawer or cabinet cavities.
- Best to avoid having them in your living space that to be searching them out to kill them.