ANR-1109 CHIGGERS
ANR-1109, New Aug 1998. Renee
R. Anderson, Graduate Student, and Faith M. Oi,
Extension Entomologist, Assistant Professor, both in
Entomology at Auburn University
Chiggers |
What Are Chiggers?
Chiggers, or "red bugs," are not insects. They are
the larval stage of mites that belong to the family Trombiculidae.
Mites belong to the Acari, the same group of organisms as ticks.
The typical mite passes through four life stages: egg, larva,
nymph, and adult.
Chiggers have six legs, are less than 1/50 inch long, and are a red-orange color. They
feed on reptiles, amphibians, small mammals, and birds, which
are their normal hosts. People are "accidental" hosts.
Chiggers that attach to humans usually die within 24 to 72 hours
because the human immune reaction to a bite prevents the chigger
from obtaining adequate nourishment.
Chigger Facts
- Chiggers do not burrow into the skin or suck blood. Rather,
they suck tissue fluids with their mouthparts. A chigger attaches
to its host, injects digestive enzymes into the bite wound, and
then sucks up the digested tissue.
- After it has completed its meal, the chigger drops off the
host and molts into an eight-legged nymph. If it is successful
in finding food, the nymph molts into an adult mite. Both the
nymphal and adult stages no longer depend on a host but feed
on small insects and various arthropod eggs. The mite life cycle
is typically 2 to 12 months. The female Trombiculid mite lays
eggs singly or in small clusters.
- Chiggers do not move far from their hatching site. This is
why people encounter "chigger patches" rather than
one or two chiggers at a time. The chiggers that attach to humans
are often encountered in two types of habitats: second-growth,
brushy areas of shrubs and brambles and low-lying, damp areas
of vegetation bordering marshes and swamps. These habitats are
areas where chiggers' preferred hosts (rodents and lizards) often
live.
Why Are Chiggers a Problem?
Chigger bites can cause terrible itching and weeping, red welts
that can continue long after the mites have died. The itching
may last up to 2 or 3 weeks and can be especially miserable if
the person is suffering from numerous bites. Scratching and secondary
bacterial infection can make it more difficult for bites to heal.
Be sure to keep the bite wound clean and dry, and apply an antibacterial
lotion if necessary.
Why Do Chigger Bites Itch So Much?
The itching is the result of the human immune system responding
to components in the chigger saliva that has been injected into
the skin. Some people may be overly sensitive to chigger bites
and experience fever. However, chiggers are not known to transmit
diseases to people in North America.
Chigger bites do not cause much discomfort in their normal
hosts.
What Can I Do To Prevent Chigger Bites?
In Alabama, the "chigger season" typically starts
in mid- to late spring and lasts through late summer. The best
means of protection is to avoid chigger habitats during this period.
Unfortunately, this is not always practical.
If you will be in a chigger habitat, avoid brushing up against
thickets and tall grass. Wear closed shoes, socks, long pants,
and a long-sleeved shirt. Tuck your pant legs into your socks
and your shirt into your pants. Use insect repellents that contain
diethyl toluamide (DEET) around the tops of your socks, your waist,
and your ankles to help keep chiggers from getting under your
clothes. Chiggers tend to like areas where clothing is the most
snug, such as around the ankles, the backs of the knees, the groin,
the waistline, and the underarms. Repellents containing permethrin
(0.5%) are excellent chigger deterrents but should be sprayed
on clothing only. Never spray Permethrin directly on skin. Always
follow the directions on the label. Repellents containing permethrin
and DEET can be found in camping or outdoor sections of most large
stores.
If you have been in a chigger habitat, take a very warm bath
or shower, preferably within the first 1 or 2 hours of being exposed.
If chiggers have not yet attached, use a soapy wash cloth to help
remove them. Signs of discomfort from chigger bites usually start
within 6 to 12 hours.
What Can I Do To Relieve the Itching?
To reduce discomfort, apply an anti-itch cream that contains
hydrocortisone, benzyl benzoate, or calamine. Some people may
be sensitive to these medications, so if you have questions, be
sure to ask your health-care professional or pharmacist.
How Do I Control Chiggers?
Controlling chiggers is difficult. Chiggers are found in areas
where their normal hosts live. These areas can include or be near
your lawn, picnic areas, and other recreational areas.
Chigger populations can best be reduced through vegetation
management. Keep grass short. Sunlight that penetrates the grass
will make the lawn drier and make it less favorable for chigger
survival.
If possible, keep rodents and other small mammals that may
serve as chigger hosts out of your yard. One thing that may help
is to remove brush and wood debris where potential mite hosts
may live. If chiggers are a serious problem, you may want to put
up a fence to keep animals away. Also, keep trash can lids secured
to discourage wildlife from coming on your property.
Chemicals that contain permethrin, cyfluthrin, diazinon, and
carbaryl (Sevin) can be used to treat outdoor areas that you use,
such as the brush borders between the lawn and woods and along
fences and paths. Broadcasting insecticides over large areas is
discouraged. See Extension publication ANR-500B, Alabama Pest
Management Handbook--Volume 2, for current chemical recommendations.
For more information, contact your county
Extension office. Look in your telephone directory under your
county's name to find the number.
For more information, contact your county Extension office. Visit http://www.aces.edu/counties or look in your telephone directory under your county's name to find contact information.
Issued in furtherance of Cooperative Extension work in agriculture and
home economics, Acts of May 8 and June 30, 1914, and other related
acts, in cooperation with the U.S. Department of Agriculture. The Alabama
Cooperative Extension System (Alabama A&M University and Auburn
University) offers educational programs, materials, and equal
opportunity employment to all people without regard to race, color,
national origin, religion, sex, age, veteran status, or disability.
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