Before modern chemicals were available, folks used natural insect repellants. "The herbs most well known for their insect-repelling abilities are bay leaf, chamomile, cinnamon, cloves, garlic, lavender, lemongrass, neem leaf, mugwort, pennyroyal, rosemary, rue, santolina, southernwood, tansy, and thyme." Which Herbs Are Natural Insect Repellants?
Your cat will tell you that pennyroyal is nasty stuff. It is. Don't get it around pregnant woman.
Great link. Thank you for that.