According to www.animal.discovery.com-
Chiggers are the larvae of mites. Like ticks and spiders, mites go through three biological stages in their life cycle: They begin as eggs, hatch as larvae, develop into nymphs and finally become adults. Nymph and adult harvest mites feed mostly on plant life and don't bother people or other mammals, but in the larval stage, many of the species are parasitic. After a parasitic chigger hatches, it finds a good position on tall grass or other vegetation so it can spring onto a passing animal. When it finds an animal, it attaches to the animal to gather the protein it needs to grow into the nymph stage.
Chiggers do not burrow under your skin, as many people believe, nor do they feed on animal blood. They actually feed on the fluids in skin cells. To get the fluids, they attach themselves to a skin pore or hair follicle and inject a digestive enzyme that ruptures the cells. The enzyme also hardens the surrounding skin tissue, forming a sort of straw for sucking the skin cell fluids. The whole process irritates the skin, causing an itchy red bump that continues to cause discomfort for several days. Chiggers are only about 1/50th of an inch (0.5 mm) in diameter and so are too small to be seen with the naked eye. This invisibility is the reason so many people believe chiggers burrow under the skin.
Obviously NOT a fun ordeal!
Recently a friend of mine, who loves to hike in the woods, found herself eaten up with chiggers. After a few sleepless nights and painful days, she read online that lavender essential oil just might help a bit.
Sure enough, a few minutes after lightly applying the oil to the worst of her bites, she no longer felt like "ripping her skin off" (a direct quote)!
Just another good reason to keep a bottle of lavender essential oil in your medicine cabinet...