R.M.
When my daughter was about that age she became deathly afraid of spiders. If she saw a spider in the car she wouldn't sit in that seat any more. If she saw a spider in her bed, she wouldn't go near her bed. An insecticide would have been unhealthy for her, so I decided to go with the placebo effect and used an air freshener. She was convinced that this spray was protecting her from spiders, and even if she saw a spider, was willing to use extra spray to protect herself. The extreme phase lasted about a year. She's still hates spiders but doesn't let it rule her universe.