After unsuccessfully trying to maintain a garden on our roof (how many times would you climb a ladder with buckets of water in your hands?), Jeff and I decided to grow veggies and herbs inside this year. Within a few days, our herbs were being taken over by these teeny tiny flies that apparently LOVE thyme more than anything else on earth. After a little research, I developed a natural insecticide that the bugs absolutely hate. You have to spray the whole plant and soil every few days to once a week, but the benefit is that you can still eat your harvest after a little washing!
DIY Natural Insecticide
- 4 jalapenos, roughly chopped
- 3 scotch bonnet peppers, roughly chopped
- 12 garlic cloves, minced
- 4 yellow onions, quartered
Place everything in a large stock pot and fill with water. Simmer for about 20 minutes over medium heat. Strain liquid into a large jar, bowl or pitcher. Stir in some natural dish soap, like Seventh Generation, and cool. Funnel into a sprayer when you need it and store in the fridge for a couple weeks.
delia-hauser.com 
Oh, I forgot a very important disclaimer!…Be careful breathing deeply as you spray this stuff since its a few steps away from being homemade pepper spray! 😉
I’ll second that pepper spray comment based on personal experience.