Controlling Chiggers 1976 -- Southern Region Agricultural Research Service Home and Garden Bulletin...|
Controlling Chiggers |
Agricultural Research Service
Home and Garden Bulletin 137, USDA, 1967
Revised April, 1976
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DC BRANCJf J
Home and G a r d e n B u l l e t i n No. 137
AGRICULTURAL RESEARCH SERVICE
U.S. DEPARTMENT OF A G R I C U L T U R E
Agricultural Research Service
This bulletin supersedes Leaflet 403, "Chiggers: How To Fight Them."
Washington, D.C. Revised April 1976
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Chiggers, sometimes called red
bugs, make up a family .of mites.
Five species found in the United
States commonly attack man.
Chigger bites cause intense itch-
ing and small, reddish welts on the
skin. You may notice these symp-
toms in the summer after working
in the garden, walking in the woods
or fields, picking berries, or mowing
the lawn. The symptoms may be
your only way of knowing that you
have been in an infested place, be-
cause chiggers are so small that most
persons cannot see them without a
Chiggers are found throughout
the continental United States.
You can use a repellent to pre-
vent attacks by chiggers if you go in
an area known to be infested. If you
get in an infested area without
knowing it, you can reduce itching
by bathing and by applying an anti-
septic and a local anesthetic to the
welts. You can get rid of an infesta-
tion by spraying or dusting the
infested area with an insecticide.
Adult chiggers pass the winter in
protected places and become active
in the spring. A few days after the
females become active they lay
eggs in sheltered places. These eggs
hatch into the first generation of
The young chigger is known as a
larva. It is the troublemaker. It is
a parasite—feeds on man and ani-
mals. The larva transforms to a
nymph, and the nymph to an adult.
Neither the nymph nor the adult is
Chiggers raised experimentally
complete the life cycle—from egg to
egg—in about 50 days.
In southern Florida and southern
Texas, chiggers may be present
throughout the year. In other
States, the chigger season begins in
May, June, or July and lasts until
September or the first frost.
In the larval stage chiggers are
orange yellow or light red. They are
less than Kso inch in diameter. The
bodies are hairy. A larva has three
pairs of legs. Its mouth parts in-
clude two pairs of grasping palps,
which are provided with forked
The nymphs and adults have four
pairs of legs. The bodies are hairy,
about Ko inch long, and usually a
brilliant red. There is a marked
constriction in the front part of the
Young chiggers attach themselves
to the skin of people or to the skin
of domestic animals, wild animals
(including reptiles), poultry, and
Before settling down to feed,
chiggers scurry around for a suit-
able location. The preferred loca-
tions on people are those parts of
the body where clothing fits tightly
over the skin, or where the flesh is
thin, tender, or wrinkled.
Like ticks, they attach themselves
by inserting their mouth parts in
the skin—frequently in hair follicles
or pores. They inject a fluid into the
skin; the fluid dissolves the tissues;
the chiggers suck up the liquefied
When they attach themselves to
A Species of Chigger (Eutrombicula batatas)
1. Unengorged larva
2. Engorged larva
From Miehener. Ann. Ent. Soc. Amer. 1946
animals, they become engorged in
about 4 days. Then they drop off
and change to nymphs.
Nymphs and the adults feed on
insect eggs, small insects, and orga-
nisms found on or near woody
EFFECTS OF ATTACK
The fluid injected into the skin by
the chiggers causes reddish welts to
appear. It also causes swelling, itch-
ing, and (in some persons) fever.
Chigger bites have a more severe
effect on some persons than on
others. Persons who are exposed
repeatedly may develop immunity
to the bites.
A chigger attached in a pore or at
the base of a hair may be so en-
veloped in swollen skin that it ap-
pears to be burrowing into the skin.
This fact sometimes leads persons to
believe, mistakenly, that chiggers
embed themselves in the skin, or
that welts contain chiggers.
Any welts, swelling, itching, or
fever will develop within 24 hours
after the attack. Itching may be in-
tense and, if nothing is done to re-
lieve it, may continue a week or
longer. Scratching a bite may break
the skin and result in infection.
Chiggers attacking in large num-
bers can cause serious injury to
poultry. They sometimes cause the
death of young chickens.
Chiggers are not known to trans-
mit any disease in this country. In
some parts of the world, particu-
larly in parts of the Far East, they
transmit scrub typhus, a serious dis-
ease similar to spotted fever. In this
country spotted fever is transmitted
Chiggers are most often found in
low, damp places where vegetation
is rank—for example, berry patches,
orchards, woodlands, and margins
of lakes and streams. But some
species are adapted to living in drier
places where vegetation is low, and
heavy infestations may be found in
lawns, golf courses, and parks.
You cannot tell by looking at a
place whether it is infested. Chig-
gers may be numerous in a place one
year, and scarce or absent another
year; and they occur in some places
only for short periods.
Before going into a place where
chiggers may be, protect yourself
against them by using a repellent.
Several highly effective repellents
are available. They do more than
repel. Chiggers that attempt to
crawl over clothing or skin areas
treated with the materials are
Repellents can be used to obtain
either temporary or long-lasting
protection. Used the first way, they
are effective several hours; the
other way, several days.
The following repellents are effec-
tive against chiggers—deet (diethyl-
dimethyl phthalate, di-
methyl carbate, and ethyl hexane-
diol. They are also effective against
mosquitoes and some other insects.
Go to a drugstore, hardware store,
or any other store where insecticides
are sold. Ask for any one of the
Applying repellent to socks and cuffs of
trousers for protection against c h i g g e r s .
repellents by name. You may be
offered a product that contains two
or more of the repellents. Such a
product is acceptable. The repel-
lents are effective individually or in
Apply the repellent to clothing by
rubbing it on, by applying it directly
from the bottle, or by spraying it
on. Some kinds of rayon and some
other manmade fabrics may be
harmed by the repellent; nylon, cot-
t.on, and wool will not be harmed.
Apply the repellent lightly, with
the fingers, to the arms or legs if
they are not covered by clothing.
Treat socks or stockings after you
put them on. Apply a ring of
repellent just above your shoe tops.
Treat all the way around the upper
edges of the hose. Cotton and wool
socks absorb repellent better than
other materials and are preferred
for wearing in chigger-infested
In treating other clothing, apply
the repellent along the edges of all
openings, inside and outside. Be-
sides treating openings that are but-
toned, zippered, or otherwise fas-
tened, treat such openings as the
In trousers and slacks.—Cuffs
In shirts and blouses.—Cuffs (or
armholes) and neckband.
In skirts.—Hem and waistband.
In dresses.—Neckline and skirt
hem; cuffs, sleeve hems, or arm-
To rub a repellent on clothing,
pour about a dozen drops in the
palm of one hand, rub the hands to-
gether, then rub lightly the parts of
the clothing to be treated.
To apply it directly from the bot-
tle, press the bottle opening against
the clothing and move it over the
parts to be treated.
To spray a repellent on clothing,
use an ordinary hand sprayer—the
kind used in homes for applying fly
Do not saturate the cloth with re-
pellent. If a garment is moist with
repellent along all openings—inside
and outside—it has been adequately
If the infested place is one in
which the vegetation is low, if you
intend merely to walk in it, and if
you are wearing trousers or slacks,
you need only apply repellent to the
cuffs of the trousers or slacks and to
socks or stockings.
Long-lasting protection against
chiggers is needed chiefly by men
who work regularly in infested areas
and by others—such as campers,
hikers, and hunters—who may be in
such areas several days at a time.
The protection is obtained by im-
pregnating clothing with a diluted
repellent or by spraying an undi-
luted repellent on the clothing.
Buy 50-percent deet, or full-
strength dimethyl phthalate or
Impregnating the clothing
Two fluid ounces of repellent are
needed to treat an ordinary set of
work clothes—shirt, trousers (or
overalls), and socks.
Prepare a solution by adding the
repellent to 3 pints of any dry-
cleaning fluid. After all parts of the
garments have been saturated with
the solution, let the cleaning fluid
Prepare an ernlusion as follows:
(1) Put % ounce of soap powder
(but not synthetic detergent) or
thinly sliced soap in 1 quart of
water and stir until the water is
soapy. (2) Take one cupful of the
soapy water, add 2 ounces of the
repellent, and stir vigorously. (3)
Pour this into the rest of the soapy
water and stir vigorously.
Place the clothes in a container
and slowly pour on the emulsion.
Work the clothes around in the
liquid. Wet them uniformly but do
not let them soak. Wring them and
hang them out to dry.
Deet or dimethyl phthalate gives
protection for at least a week, un-
less washed out of the clothing.
Laundering washes out the repel-
lent; a heavy rain may do so. Repel-
lent in trousers and socks is washed
out if the wearer wades through
water. Re-treat the clothing after
Benzyl benzoate is effective long-
er than deet or dimethyl phthalate,
and it washes out less readily. It
gives protection even after clothing
has been laundered twice. Clothing
that has been laundered twice since
being treated should be re-treated.
In addition to providing complete
protection against chiggers, either
of these treatments gives consider-
able protection against ticks.
Spraying the clothins
In spraying to obtain long-lasting
protection, you apply the repellent
to the entire garment—not just to
the openings. Using a hand sprayer,
apply a mist of full-strength di-
methyl phthalate or benzyl benzoate
on the outside of the clothing and
on your shoes and socks; continue
until the clothing is slightly moist,
but not wet. Do not apply more
than 2 ounces of repellent to a set of
work clothes. Let the clothes dry for
several hours before wearing them.
Deet is available at 12 to 15 percent
in pressurized spray cans. Follow
directions on the labels.
It is easier to spray clothes than
to put them through the impregna-
tion treatment, but it is difficult to
apply the spray uniformly. Also,
spruyed-on repellent loses its effec-
tiveness a few days sooner than re-
pellent applied by impregnation,
and it is washed out more easily.
REDUCING THE ITCHING
If you get in a chigger-infested
place without the protection of a re-
pellent, attack is almost certain.
You may not know that you have
been attacked until welts appear on
the body and itching begins.
Take a bath as soon as possible.
Apply a thick lather, then rinse it
off. Do this several times. The bath
kills most, or all, of the attached
chiggers, and any others that may
not yet be attached.
Next, apply a dab of antiseptic to
each of the welts. This will kill any
chiggers not killed by the bath, and
it aids in preventing infection.
Destroying the chiggers reduces
the itching, but does not stop it. The
fluid injected by the chiggers causes
the itching. No practicable way to
remove it has been found, and no
treatment is known that will give
permanent relief from the itching.
To get temporary relief, apply a
local anesthetic. The following for-
mula has been found helpful:
Methyl salicylate, 2 percent.
Salicylic acid, 0.5 percent.
Ethyl alcohol, 73 percent.
Water, 19.5 percent.
Take the formula to your drug-
gist for compounding. Apply the
material to each welt with a piece
of cotton. One treatment gives relief
for an hour or longer. Repeat the
treatment as often as necessary.
Some persons who have had ex-
perience with chiggers can detect
an attack without the evidence of
- Proprietary ointments containing ben-
zocaine are also useful.
Applying insecticide with a rotary hand duster.
welts and itching. They feel the
slight irritation that is produced
when the chiggers begin to attach,
and they know what is causing it.
They may feel the movement of
chiggers as they crawl on the body
seeking a place to attach.
If you become aware of sensations
that cause you to suspect the pres-
ence of chiggers, examine the skin.
Look carefully at the bases of hairs.
You may not be able to see the chig-
gers, but you may be able to see
small reddish spots where they arc
The more quickly you detect the
chiggers, the better results you will
get from the soapy bath. If you can
take the bath within an hour after
the chiggers get on you, it will prob-
ably kill most of them before they
You can wipe out a chigger in-
festation by applying an insecticide
spray or dust in the infested area.
Apply the spray or dust to grass,
logs (and the ground around them),
and ground litter. Apply it around
bushes and high weeds.
The recommended insecticides arc
toxaphene, lindane and diazinon.
They can be purchased in insecticide
supply stores, and arc generally
available in the form of cmulsifiable
concentrates, wettablc powders, and
dusts. Select any one of the insecti-
cides, and decide in what form you
wish to buy it.
An emulsifiable concentrate or
wettable powder is mixed with
water to make a spray. A dust ia
ready to use when purchased.
An emulsion spray, prepared by
mixing an emulsifiable concentrate
with water, usually gives better re-
sults than a wettablc-powder spray
or a dust.
Locating the Chiggers
Before you start applying an in-
secticide, have a clear idea of where
the chiggers are. If the area is a
large one, such as a picnic ground,
Applying insecticide with a garden-type compressed-air sprayer.
a golf course, or a large lawn, it may
be advisable to make a simple sur-
vey. The chiggers may be concen-
trated in a few spots within the
area. Treating the trouble spots is
quicker and less expensive than
treating the whole area, and less
likely to damage wildlife.
Place a piece of black card-
board edgewise on the ground. Ob-
serve it for a few minutes. If chig-
gers are present, they will climb to
the top edge and congregate there.
Make the test in about a dozen spots
over the area. Pick out spots that
have different kinds of cover, such
as solid growths of grass, tufts of
grass, dead leaves, and decaying
twigs. Remember, you are chigger
hunting; you should be protected
by a repellent.
Unless the entire area is infested,
treat only the parts in which con-
trol is especially desired, such as
grass around picnic tables or lawn
Emulsifiable concentrates and
wettable powders contain various
percentages of insecticide. The per-
centages shown in the accompany-
ing chart are those most commonly
found in retail products.
To prepare a spray, mix one of
the products with water in the
proportion indicated in the chart.
Apply the finished spray as follows,
but do not treat areas where
livestock feed or graze:
Small areas.—To treat a lawn,
campsite, or other small area, use a
cylindrical compressed-air sprayer
or a knapsack sprayer. Apply 2% to
3 quarts per 1,000 square feet (25 to
35 gallons per acre).
Federal and State regulations
require that registration numbers
must be shown on the container of a
pesticide. Use only pesticides that
carry this designation. Read and
follow all the directions on the label.
Normally USDA publications,
that contain suggestions for the use
of pesticides, are revised at 2-year
intervals. If your copy is more than
2 years old, contact your Coopera-
tive State Extension Service to
determine the latest pesticide
The pesticides mentioned in this
publication were federally registered
for the use indicated as of the time
of the issuance of the publication.
Because the registration of a
pesticide may be changed before
using a pesticide that you have had
in your possession for some time
you may wish to check with your
local agricultural authorities to
determine the registration status of
Large areas.—To treat a park,
golf course, or other large area, use
a power sprayer. To get uniform
coverage, apply twice as much spray
material as you would with a small
sprayer, but do not double the
amount of insecticide. Double the
amount of spray material by adding
Apply 50 to 70 gallons per acre.
An emulsion spray prepared and
applied according to these recom-
mendations is effective 4 to 8 weeks;
a wettable-powder spray, 2 to 6
weeks. A spray is considered effec-
tive for a stated period if few or no
HOW TO PREPARE SPRAYS FOR CHIGGER CONTROL
FORMS IN WHICH INSECTICIDES MAY BE
25 percent . -
25 percent . . .
48 percent (4 Ib/gal)
50 percent .
AMOUNT OF PURCHASED PRODUCT
To Mix WITH —
5 gallons of water
2 cups _ -
100 gallons of
Use of chlordane has been suspended by EPA.
The amounts listed are based on calculations from diazinon label's for the use of
chigger control, at an application rate of 3 quarts per 1,000 square feet. These amounts
should be verified.
active chiggers can be found in the
treated area during that period.
Apply 5-percent toxaphene dust
at the rate of 40 to 50 pounds per
acre (1 to 1% pounds per 1,000
square feet), or 1-percent lindane
dust at the rate of 50 pounds per acre
(1>4 pounds per 1,000 square feet).
A dust treatment is effective 1 to
Dusts can be applied with any
equipment that is used for dusting
plants. A rotary hand duster is ex-
cellent for treating small areas. A
power duster is better for large
areas. Do not treat areas where
livestock feed or graze.
Keep repellents away from your
eyes and mouth.
Do not treat underwear with a re-
pellent. Treated underwear may
irritate the skin.
Do not apply a repellent to stoek-
ings or other clothing t h a t contains
rayon. Repellents are damaging to
some kinds of rayon and to some
other manmade fibers, nylon is not
Do not let repellents touch paint-
ed surfaces or objects made of plas-
tic materials, such as fountain pens,
fishing rods, watch crystals, or
frames of eyeglasses.
The user is responsible for
the proper use and storage of
pesticides. Pesticides used im-
properly can be injurious to
man, animals, and plants.
.Store pesticides in original
containers under lock and
key—out of the reach of
children and animals—and
away from food and feed, seed,
other plant materials, and
fertilizer. Follow the direc-
tions and heed all precautions
U. S. G O V E R N M E N T P R I N T I N G OFFICE : 1976 O - 597-792