The spray bombs are typically good for 90-120 days, any bugs coming in, will also die off for that time period. Then again, a quality commercial bug killing company will charge $65-$70 a quarter to spray the inside and outside of your home, maybe put some bait traps for those critters a bit larger than bugs.
Don’t look in my garage..lol Gasoline, acetone, sulphuric acid, oh I could go on and on.
First, to kill the bug infestation the lizards are clearly feeding on, two, once the gas permeates and dries, the toxicity level for humans and pets is near zero (you would have to lick up to 3 sq/ft of flooring/surfaces to cause short term nausea), it is the bugs that then walk over those surfaces and the chemical reaction they have with that surface that then kills them off. Eventually, the bugs are gone, with nothing to feed on, the lizards will find a better place to hunt and feed.
Reminds me of the RoundUp dosage to cause issues. The studies are based on cancer in mice etc, apparently the equivalent human dose is something like drinking 13 gallons of it over a month... which probably explains why farmers don't have higher rates of cancer than people who never go near the stuff...
Round up is for killing weeds,
Sure, my garage is full of all kinds of toxic chemicals too. All of which are in appropriate containers, and deployed with appropriate safety precautions.
They are temporary by design, after you eradicate the main cause of the lizards, then falling back to sticky traps along the baseboard of the garage, close to the door/window openings, are the non toxic way to go from there. Without allowing a good fogging, so as to kill the nest and eggs in every hidden nook and cranny, anything else you do is a waste of time, as the eggs will hatch, or the bugs you missed will procreate, as bugs generally do, and the whole process starts again.
Living less than 15 minutes away from the OP, I have a pretty good take on the why portion, as the new house we are remodeling (two miles from our current), also had a similar infestation, but throughout the crawlspace and not the garage. The garage had nothing for the bugs to live in or around, while the crawlspace had years of construction dumping and such, and with the vents wide open (screening long chewed out by rodents), our choices were few and far between. Replacing the vents first, then having the crawlspace professionally fogged took care of the bugs, which in turn took care of the other rodents, and the lizards, as they had nothing to feed on, so went elsewhere to forage for sustenance. Have not had any rodents, nor lizards and such in the crawlspace since that time, now going on 6 months....So again, I'm speaking from experience here, both in geographic location, and the experience itself. I still catch the occasional spider and grasshopper in the sticky traps, but nothing else.....