Dengue may not be as prevalent in the U.S. as in the tropics, but the bites of mosquitoes alone are enough to annoy your guests. Mosquitoes can be deterred by playing on their sense of smell, which they rely on in seeking their targets.There are various ways to do this. First, go for plants that emit strong odors like lemon balms and citronella; if you want something with color, consider marigolds. Another way is to have plants that attract insect-eating birds like the gray catbird and yellow-headed blackbird. Fruit-bearing trees are good choices because they provide birds with both food and shelter.