Chiggers are the larva of several types of mites that attack all vertebrates except fish. The adults are herbivores that feed off of nutrients in the soil. But the immature larva feed on skin cells by injecting an enzyme into the skin cell that dissolves the cell, allowing them to consume it.
By the time a person is aware of a chigger's presence, the creature is long gone. The only evidence that a chigger has been there is a red bump and a persistent itch. Since the chigger has a very delicate mouth, it can only pierce the skin where it is thin, or along folds. This is why most chigger bites seem to occur around ankles, the backs of knees and the belt line.
To avoid chigger bites, wear long sleeves, pants and socks when outdoors. Since a chigger will generally wait an hour before feeding, you can also cut down on chigger bites by bathing in hot water after coming in from the outside. If a bath is not an option, you can dislodge chiggers before they start to feed by rubbing down with a cloth or towel. A gentle rub is all it takes to dislodge a chigger. To keep chiggers out of your yard, remove any brush or other habitat that chiggers seem to prefer.
The most effective repellent for chiggers is sulfur. Chiggers hate the smell of sulfur, and avoid areas where it has been placed. You can purchase powdered sulfur at most pharmacies. Dust it on the cuffs of your clothing, socks and shoes to repel chiggers. If you are walking in the woods, you can mix up a body powder of half sulfur, half talcum powder and rub it over your legs, arms and waist. You can also put it in a pillowcase and drag it over your lawn to chigger-proof the area for children who may be playing there. Since some people are allergic to sulfur, several natural plants including mountain mint pennyroyal and camphor are also effective. However, pregnant women should never use oil of pennyroyal.
The itch that develops from a chigger bite isn't in reaction to the chigger. A chigger's saliva kills cells and causes them to harden into a tube-like stylostome that the chigger drinks from like a straw. The itch and swelling is actually an allergic reaction to the presence of the stylostome in the body. The longer a chigger has to feed, the deeper the stylostome grows and the more it itches. To control the itch, try drinking an herbal tea with antihistamine properties such as chamomile. Chamomile and other herbal antihistamines can also prove helpful at cutting down itch when added to a bath or applied directly to the itch as a teabag poultice.