My husband had an earache. So I prepped my standard ear pain remedy: 1 clove garlic, crushed, and allowed to steep for 15 minutes in about a 1/4 cup of olive oil. Careful not to suck any garlic into the dropper (raw garlic can destroy sensitive ear innards) I applied 3 drops of oil to the opening of the ear canal, and the pain subsided.
It was late at night, the house was dark, and I was lazy. Rather than returning the garlic & olive oil jar to the kitchen, I set it on the bathroom counter. Next morning, there was a dead roach at the bottom of the jar. ewwww!
I constructed the following scenario. Attracted by the yummy garlic aroma, the roach crawls in. Greasy feet prevent escape, or possibly, the oil clogs the spiracles, holes in the exoskeleton through which insects breath. Either way, dead as a door nail. So of course, next night, I tried it again.
Now, I don't want to make it sound like we're overrun with roaches! We live in the desert and it is just too dry to support a big population of roaches in the house. In the desert, the roaches come from the sewer. They crawl out of the shower drain and snoop around in your towels and Q-tips. Nasty! Sometimes one will take up residence under the sink. You know it's the same guy each time you see him, because no roach has ever been so big, or so defiant. Well, say hello to the evictor: mason jar + garlicky oil.
|Archimylacris eggintoni, 310 million-year-old ancestral cockroach fossil http://planetearth.nerc.ac.uk/news/story.aspx?id=708|
I've read that garlic and other herbs can be used as a repellent, but my experience with the garlic oil is that roaches will jump in with six feet. Roaches are smart, sometimes it takes 2 or 3 nights to succumb to the intoxicating scent of garlic oil. Hasn't failed me yet.