Nearly all essential oils have bactericidal properties and by encouraging the production of white blood cells, they can assist in the treatment and prevention of infectious illness. Those who regularly use essential oils often become much more resistant to illnesses such as coughs and colds and have a much quicker recovery if the odd ones does catch them. Lavender, Teatree, Eucalyptus, clove, cajiput and camphor are just a few examples of good bug busting essential oils to keep close by.