Mosquitoes have complex methods of detecting hosts and different types of mosquitoes react to different stimuli. Most mosquitoes are active at dawn and dusk, but there are also mosquitoes that seek hosts during the day. You can avoid being bitten by making sure you aren't attracting mosquitoes, using attractants to lure mosquitoes elsewhere, using a repellent, and avoiding actions that diminish the effectiveness of the repellent.
Many mosquitoes use vision to locate hosts from a distance. Dark clothes and foliage are initial attractants.
You give off more carbon dioxide when you are hot or have been exercising. A burning candle or other fire is another source of carbon dioxide.
You release more lactic acid when you have been exercising or after eating certain foods (e.g., salty foods, high-potassium foods).
Floral or Fruity Fragrances
In addition to perfumes, hair products, and scented sunscreens, watch for the subtle floral fragrance from fabric softeners and dryer sheets.
The exact temperature depends on the type of mosquito. Many mosquitoes are attracted to the slightly cooler temperatures of the extremities.
Mosquitoes are attracted by perspiration because of the chemicals it contains and also because it increases the humidity around your body. Even small amounts of water (e.g., moist plants or mud puddles) will draw mosquitoes. Standing water also allows mosquitoes to reproduce.
It's very easy to make your own natural mosquito repellent. These natural products will effectively repel mosquitoes, but they require more frequent reapplication (at least every 2 hours) and higher concentrations than DEET. Because of the differences between types of mosquitoes, products that contain multiple repellents tend to be more effective than those containing a single ingredient. As you can see, natural repellents tend to be volatile plant oils.
Lemon Eucalyptus Oil
Possibly Oils from Verbena, Pennyroyal, Lavender, Pine, Cajeput, Basil, Thyme, Allspice, Soybean, and Garlic
Another plant-derived substance, pyrethrum, is an insecticide. Pyrethrum comes from the flowers of the daisy Chrysanthemum cinerariifolium.
Things that Lower Repellent Effectiveness
Dilution from Rain, Perspiration, or Swimming
Absorption into the Skin
Evaporation from Wind or High Temperatures
Keep in mind that 'natural' does not automatically imply 'safe'. Many people are sensitive to plant oils. Some natural insect repellents are actually toxic. Therefore, although natural repellents provide an alternative to synthetic chemicals, please remember to follow the manufacturer's instructions when using these products.