Chiggers are the juvenile form of a species of mite that belongs to the Trombiculidae family. They attach themselves to humans and feed on skin cells, which can lead to itching.
According to older research from the Entomology Department at the University of Kentucky, these mites commonly attach where the skin is thin, wrinkled, or tender. They also commonly attach in areas where clothing is tight.
Chiggers are very small and almost impossible to see with the naked eye. At around 1/50th of an inch in size, most people need a magnifying glass to spot them. These mites resemble tiny spiders, are red in color, and tend to cluster in groups on a person’s skin. They are usually only visible to the naked eye when in groups.
Chiggers are most common in the spring and fall months. While chiggers live across the United States, they are more common in the warmer Southern and Midwestern states.
Common places to find chiggers include:
- long and overgrown grass in fields and gardens
- grassy areas around lakes and rivers
- berry patches
- under rocks
- among weeds
- where large numbers of rodents are present
- areas of high humidity
The easiest way to help avoid chigger bites is simply by avoiding walking in long grass, bushes, or other areas where chiggers may be present. But this is not an option for everyone.
People who walk into contaminated areas
According to the Centers for Disease Control and Prevention (CDC), an effective bug spray to use on clothing is permethrin. This kills chiggers as well as mosquitoes and ticks.
If using permethrin, people should treat their clothing 1–2 days in advance to allow them to dry before being worn in the wild. People should be sure to follow the label instructions on all pesticides they may use.
If venturing into long grass, people should wear tall boots. Under these, they should wear trousers and tuck the ends of them into their socks. Finally, people should wear a belt and long-sleeved shirts. This stops the chiggers from having direct access to skin.
Once a person is out of the infested area, they should remove and wash their clothes with hot water immediately. They should then have a hot shower or bath, scrubbing the body with soap.
The less time spent among the contaminated vegetation, the fewer chances chiggers have of getting onto a person’s skin.
If a person brushes up against grass or other vegetation where chiggers are present, these mites can quickly attach to their skin. If chiggers bite someone, there are a few things they can do.
- Over-the-counter anti-itch medications: These are effective at helping prevent a person from scratching their bites. These medications typically include hydrocortisone or calamine lotion.
- Ice: If a person does not have access to medication right away, applying ice to bites can help relieve the desire to scratch.
- Bath or shower: A person should take a bath or shower when they realize they have chigger bites. Scrubbing with soap and water is a good way to remove any other chiggers that may remain on the body. This will help prevent further bites.
Chigger bites usually take between 1–3 weeks to heal. But if a bite persists for a prolonged period of time, people may wish to speak with a doctor.
A doctor may prescribe steroid shots to calm itching and swelling, though this is only in rare cases. If the bites become infected, a doctor may also prescribe antibiotics.
Contrary to popular belief, chiggers do not burrow into the skin, feed on a person’s blood, or carry disease. They feed on human skin cells, although it is only the juvenile form of the mites that do this.
When biting a human, chiggers will insert their feeding structures into the skin. Before they can eat, the chiggers inject an enzyme into the skin to liquefy the tissue. This action makes a hole in the skin, and then the skin around this hole hardens, forming a feeding tube called a stylostome.
Chiggers then feed on the destroyed tissue through this stylostome. If left undisturbed, the chiggers can feed for a couple of days.
Chiggers have delicate feeding structures. This means that they find it easier to penetrate a person’s skin where there are wrinkles, folds, or where the skin is thinnest.
Because the skin hardens around the feeding area, most people develop reddish welts within 24 hours of being bitten. Intense itching often follows.
The itching may last for a week or longer if not treated.
Are there any complications?
Chiggers in the U.S. are not known to carry or transmit diseases. But they do cause intense itching. If the bites are scratched, they may result in infection that can sometimes lead to fever.
Other biting insects and bugs to look out for
As well as chiggers, there are a number of other biting insects to be aware of. Here is a small selection that people may come across:
- Ticks: Ticks are often located in plants and brush and can bite people. While their bites are often deemed harmless to humans, they can carry diseases such as Lyme disease and Rocky Mountain spotted fever.
- Scabies: These mites burrow into a person’s skin and cause intense itching. Scabies can spread when a person comes into close contact with a person infected by the mites.
- Bedbugs: Usually found in beds and old furniture, bedbugs have a mild bite and are less than 1 millimeter long. They usually leave a small, red, itchy lump after a bite.
- Fleas: Fleas do not just bite pets. They can bite humans too. These insects suck blood from their hosts to feed, and leave small itchy lumps.
- Mosquitoes: Mosquitoes cause itchy hives on a human’s skin once they have fed. They are often harmless, but some species can carry serious diseases.
- Fire ants: Found mainly in the southern U.S., these ants have a stinger and a painful bite. Fire ant stings can be very itchy and may turn into pus-filled blisters.