Spotted gum
The spotted gum or lemon-scented gum originally came from Australia, but humans exported it around the world for its mosquito-repelling scent. The tree grows tall, with smooth white to pink bark, narrow lance-shaped to curved adult leaves, flower buds in groups of three, white flowers, and urn- or barrel-shaped fruit. It does not tolerate shade, so it has to grow in an open area, but it can flourish even in poor soil. It does need to drain well, though.
Spotted gum’s oil consists primarily of citronellal. People will weave its leaves into sleeping mats, releasing an odor as they crush the leaves in their sleep that repels mosquitoes. Steam distillation can refine the oil into an even more potent repellent.