Hoelscher, Clifford E.

English

Texas A&amp;M Repository

SPIDER MITES IN THE HOMEGARDEN AND LANDSCAPEClifford E. HoelscherArea Extension EntomologistThe Texas A&M University SystemL-1244Spider Mite.There are numerous mite species which attackhorne lawns, vegetable gardens and ornamental plants,and they can become extremely destructive. Mites arenot insects but are frequently referred to as insect-like pests. Mites are classified with spiders, belongingto the Class Arachnida, Order Acarina, and have eightlegs in the adult stage. These pests are small in size(approximately one-eighteenth of an inch in length)and round in shape. They are barely visible to thenaked eye. When viewed with a magnifying glass, theyappear to be sparsely covered with long, rigid hairs. Atypical diagrammatic drawing of amite is presentedin Figure 1.This publication is designed to provide thehomeowner with information on identifying. andcontrolling damaging mite infestations.Life Cycle and DevelopmentMite populations initially develop on the under-sides of plant leaves. The reproductive potential ofmites is extremely high, and in periods of hot, dryweather mites can complete a life cycle from egg toegg in approximately 5 days. Generally 7 to 14 daysPlant infested with spider mites.are required for mites to complete a life cycle.Females are known to lay up to 300 eggs in only afew days. Thus, rapidly increasing mite populationscan cause extensive plant damage before the home-owner becomes aware of the problem.Mite eggs are usually oval in shape and mayvary from a cream color to orange or bright red. Theeggs usually hatch in 2 to 4 days and will hatch morereadily during warmer periods. Mites usually over-winter in the egg stage, however some remain activethroughout the year. Eggs deposited in late fall willhatch in early spring to initiate the first generation.Larval StageAfter mite eggs hatch, the larval stage appears,which is characterized by having only three pairs oflegs. The females molt three times in the course oftheir growth, and the males molt only twice. In theadult stage mites have eight legs and are approxi-mately one-sixtieth to one-eightieth of an inch inlength. Most adults spin small threads of silk duringtheir feeding activities, which aid in securing the eggsto the leaf.Texas Agricultural Extension Service. The Texas A&M University System. John E. Hutchison, Director. College Station, TexasTwo-Spotted Spider MiteDescription and Life History: The two-spottedspider mite, Tetranychus bimaculatus, belonging tothe family Tetranychidae, is the most commonspecies of mites attacking home gardens andornamental plants. The adult female is eight-leggedand pale yellowish or greenish in color. These mi teshave two dark spots, composed of food content,showing through the transparent body wall. The bodyis oval in outline and sparsely covered with spines.The mites feed through sucking mouthparts whichpierce the epidermis of the leaf. After mating, thefemale mite begins laying eggs at a rate of from twoto six a day and will deposit a total of 70 or moreeggs during her lifetime. A complete generation isproduced every 20 to 40 days, but generationsoverlap so that all stages of mites may be found onplants at any time.Damage: Leaves of plants infested by spidermites develop a characteristic appearance. Lightlyinfested plants have pale yellow blotches or spotsshowing on the upper leaf surface. With heavyinfestations, the entire leaf appears light in color,becomes desiccated, and often turns reddish-brown inspots or around the edge. Plants generally lose theirvigor and often die. The undersurfaces of lightlyinfested leaves have silken threads spun across them.Where large populations develop, these threads mayform a web over the entire plant. Mites crawl on thisweb and attach their eggs to it. Mites appear on theundersides of leaves as tiny reddish, greenish,yellowish or blackish moving dots. Mite color mayvary according to the kind of plant food available.Red Spider MiteDescription and Life History: Members of thisgroup are often very red to orange in color. Thesemites belong to the family Tetranychidae andrepresent members of the genera Paratetranychus andalso Tetranychus. The most common of the redspider mites is the six-spotted spider mite,Tetranychus sexmaculatus. The eggs, which appearred just before hatching, are fastened to the leaves orto the silk spun by the mites. There are three growingstages of the six-legged larvae and two eight-leggednymphal stages. The larvae and nymphal stages differmainly in size. The adult red spider mite is velvety redor purple in color, with about 20 prominent bristlesover the body. In the adult stage, the six-spottedspider mite has eight legs, is purplish, greenish oryellowish, and sometimes has six dark spots. Ageneration is usually completed in 3 to 5 weeks.Damage: This mite usually causes leaf damageby extracting chlorophyll, which gives the leaf asilvery or speckled appearance. Feeding activity ofthese mites is usually restricted to areas on theundersides of the leaves where the mi te coloniesform. These areas become depressed and yellow.Webbing appears underneath the swollen, yellowspots on the upper surfaces of the leaves.Bermudagrass MiteDescription and Life History: Bermudagrassmites, Aceria cynodoniensis, are very small, eight-legged pests that have caused considerable damage tobermudagrass lawns in many western areas of Texas.These cigar-shaped mites can be readily distinguishedfrom the oval-shaped mites commonly seen aroundthe home. Females lay eggs in protected places on thegrass. The larval stage, with only six legs, is followedby a nymphal stage which has eight legs, as do theadults. The life cycle of this mite is completed inabout a week, and because they can multiply rapidly,extensive damage can be caused in a short period oftime.Damage: Bermudagrass mite damage resultsfrom the removal of plant sap from the stems andleaves, which causes yellow or brown areas and agenerally unhealthy appearance. Characteristicsymptoms of injury are short internodes which causethe grass to have a bushy or tough appearance. Whenmite damage is severe, the grass is severely thin, andweeds usually take the place of the dead grass.~anksgrass MiteDescription and Life History: The banksgrassmite, Oligonychus pratensis (Banks), has been aproblem in the West and High Plains areas of Texas.This mite is oval and very similar to the two-spottedmite. Chemical control of this species has beendifficult because of its high level of resistance torciticides. Eggs are transparent in color and hatch in Ito 2 days. Approximately 7 to 14 days are requiredfor completion of a life cycle. The banksgrass mitemay infest grasses and many ornamental plants.Damage: Plant injury is similar to that causedby the two-spotted spider mite.Chiggers, Jiggers and RedbugsMany people are not aware that the common"redbug" or chigger is actually amite. The larvalstage of this mite feeds on the skin of man anddomestic animals, rather than on plants, and causes asevere itching sensation. These mites are members ofthe family Trombidiidae and are discussed in detail inanother publication.Spider Mites on VegetablesThe two-spotted mites usually are quite aproblem on vegetables produced in the home garden,especially during periods of hot, dry weather. Plantsseverely attacked include tomatoes, eggplants, beansand corn.Damage: Mites pierce leaf tissue and suck plantsap in the larval, nymphal and adult stages. Plantsbegin to lose color, fading from green to yellow, andeventually turning reddish. Heavy infestations cancompletely kill plants such as tomatoes. The under-sides of plant leaves should be checked carefully andfrequently for developing mite infestations.Mite ControlChemical controls for mites in the home gardenare suggested in Table 1, and a list of miticides thatcan be applied to the home landscape is given inTable 2. Mite control is often difficult because ofresistance to the miticides being used. The home-owner must be sure to achieve complete spraycoverage of infested plants. Most of the miticides arecontact materials, and the spray solution must comein contact with the mites to achieve satisfactorycontrol. Repeat applications (two to four) aregenerally required for satisfactory control. Frequentplant inspection is the best means of determining theneed for additional applications. Read all labeldirections carefully before using a miticide material.Store all unused materials in a locked area to avoidaccidental poisoning of small children or pets.Table 1. Suggested miticides for the home garden and days from last spray application to harvest.• 00 not use; not an Environmental Protection Agency registered use.OiazinonBeansBeetsCantaloupesCarrotsCornCucumbersMustard greens3 days10 daysNone(pre plant ortransplant only IKelthane Malathion Sulfur Ethion7 days l 1 day odays 2 days24 days310 days4odaysodaysodays5 days odays 50 days5(field)1 day No preharvestintervalOkraPeanutsPeasPeppersPotatoesSquashTomatoes 1 dayWatermelons1 day7 days odays3 days2 days6 odays7(0.5Ib/acrel21 days(1.0Ib/acrelodays2 days8 odays No preharvestinterval(summer)2 days9 5 days10 odays 2 days121 day 11 28 days132 days14 odayslPreharvest interval through 0.6 Ib/A spray or 1.5 Ib/A dust (beans-45 day preharvest interval from 0.6 through0.81b/A spray as a foliage application on dry beans only).20.5 Ib/A spray or 0.81b/A dust.31.0 Ib/A spray or 1.61b/A dust.41.5 IblA-Do not make more than one application after the edible parts have formed.500 not apply more than once after ears have formed.6Preharvest interval through 0.81b/A spray or 1.5 Ib/A dust-foliage application.700 not apply more than three times during fruiting period (applicable to the 1.0 lb. rate).8Preharvest interval through 0.6 Ib/A spray or 1.5 Ib/A dust.9preharvest interval through 0.81b/A spray or 1.5 Ib/A dust-foliage application.l03.51b/A as a dust or diluted spray.112.0 Ib/A as a dust or diluted spray; 0.61b/A as an undiluted (low volume) spray.120.5 Ib/A spray or 0.8 Ib/A dust.131.2Ib/A-Do not apply more than once after fruit begins to form.14Preharvest interval through 0.61b/A spray or 1.5 Ib/A dust.Table 2. Suggested miticides for the home landscape.C)...~'N cc c C) 0 c.! 0 c :.c c.2c ca ~(5 'N ~ ... ::J 0 ~... ca :!: :.c ...:c ca 1) on;c ~ ::J ....;:U ~ en w I-Bermudagrass XXXXXHouse plants X XRoses XXXX XOrnamental citrus XXX XWoody shrubs XX X XMarigolds X X XXPecans XXXXSpring flowering annuals XXXX XSummer flowering annuals X X X XFollow label directions carefully for rates of applica-tion.Table 3. Dilution chart for hand sprayers for homeowner use.DiazinonDicofal (Kelthane)MalathionSulfurEthionChlorbenzilateTrithion%Emulsion2518.550Tsp./Gal.Water222% WettablePowder100255025Tsp./Gal.Water9686Use about 1 quint of spray or 1.5 oz. of dust per 50 feet of row.Educational programs conducted by the Texas Agricultural Extension Service serve people ofall ages regardless of socio-economiclevels, race, color, sex, religion or national origin.Cooperative Extension Work in Agriculture and Home Economics, The Texas A&M University System and the United StatesDepartment of Agriculture cooperating. Distribu ted in furtherance of the Acts of Congress of May 8, 1914, as amended, and June30, 1914.7%.M-5-74 LH3

Spider Mites in the Home Garden and Landscape.

Texas A&M University

SPIDER MITES IN THE HOME
GARDEN AND LANDSCAPE
Clifford E. Hoelscher
Area Extension Entomologist
The Texas A&M University System
L-1244
Spider Mite.
There are numerous mite species which attack
horne lawns, vegetable gardens and ornamental plants,
and they can become extremely destructive. Mites are
not insects but are frequently referred to as insect-
like pests. Mites are classified with spiders, belonging
to the Class Arachnida, Order Acarina, and have eight
legs in the adult stage. These pests are small in size
(approximately one-eighteenth of an inch in length)
and round in shape. They are barely visible to the
naked eye. When viewed with a magnifying glass, they
appear to be sparsely covered with long, rigid hairs. A
typical diagrammatic drawing of amite is presented
in Figure 1.
This publication is designed to provide the
homeowner with information on identifying. and
controlling damaging mite infestations.
Life Cycle and Development
Mite populations initially develop on the under-
sides of plant leaves. The reproductive potential of
mites is extremely high, and in periods of hot, dry
weather mites can complete a life cycle from egg to
egg in approximately 5 days. Generally 7 to 14 days
Plant infested with spider mites.
are required for mites to complete a life cycle.
Females are known to lay up to 300 eggs in only a
few days. Thus, rapidly increasing mite populations
can cause extensive plant damage before the home-
owner becomes aware of the problem.
Mite eggs are usually oval in shape and may
vary from a cream color to orange or bright red. The
eggs usually hatch in 2 to 4 days and will hatch more
readily during warmer periods. Mites usually over-
winter in the egg stage, however some remain active
throughout the year. Eggs deposited in late fall will
hatch in early spring to initiate the first generation.
Larval Stage
After mite eggs hatch, the larval stage appears,
which is characterized by having only three pairs of
legs. The females molt three times in the course of
their growth, and the males molt only twice. In the
adult stage mites have eight legs and are approxi-
mately one-sixtieth to one-eightieth of an inch in
length. Most adults spin small threads of silk during
their feeding activities, which aid in securing the eggs
to the leaf.
Texas Agricultural Extension Service. The Texas A&M University System. John E. Hutchison, Director. College Station, Texas
Two-Spotted Spider Mite
Description and Life History: The two-spotted
spider mite, Tetranychus bimaculatus, belonging to
the family Tetranychidae, is the most common
species of mites attacking home gardens and
ornamental plants. The adult female is eight-legged
and pale yellowish or greenish in color. These mi tes
have two dark spots, composed of food content,
showing through the transparent body wall. The body
is oval in outline and sparsely covered with spines.
The mites feed through sucking mouthparts which
pierce the epidermis of the leaf. After mating, the
female mite begins laying eggs at a rate of from two
to six a day and will deposit a total of 70 or more
eggs during her lifetime. A complete generation is
produced every 20 to 40 days, but generations
overlap so that all stages of mites may be found on
plants at any time.
Damage: Leaves of plants infested by spider
mites develop a characteristic appearance. Lightly
infested plants have pale yellow blotches or spots
showing on the upper leaf surface. With heavy
infestations, the entire leaf appears light in color,
becomes desiccated, and often turns reddish-brown in
spots or around the edge. Plants generally lose their
vigor and often die. The undersurfaces of lightly
infested leaves have silken threads spun across them.
Where large populations develop, these threads may
form a web over the entire plant. Mites crawl on this
web and attach their eggs to it. Mites appear on the
undersides of leaves as tiny reddish, greenish,
yellowish or blackish moving dots. Mite color may
vary according to the kind of plant food available.
Red Spider Mite
Description and Life History: Members of this
group are often very red to orange in color. These
mites belong to the family Tetranychidae and
represent members of the genera Paratetranychus and
also Tetranychus. The most common of the red
spider mites is the six-spotted spider mite,
Tetranychus sexmaculatus. The eggs, which appear
red just before hatching, are fastened to the leaves or
to the silk spun by the mites. There are three growing
stages of the six-legged larvae and two eight-legged
nymphal stages. The larvae and nymphal stages differ
mainly in size. The adult red spider mite is velvety red
or purple in color, with about 20 prominent bristles
over the body. In the adult stage, the six-spotted
spider mite has eight legs, is purplish, greenish or
yellowish, and sometimes has six dark spots. A
generation is usually completed in 3 to 5 weeks.
Damage: This mite usually causes leaf damage
by extracting chlorophyll, which gives the leaf a
silvery or speckled appearance. Feeding activity of
these mites is usually restricted to areas on the
undersides of the leaves where the mi te colonies
form. These areas become depressed and yellow.
Webbing appears underneath the swollen, yellow
spots on the upper surfaces of the leaves.
Bermudagrass Mite
Description and Life History: Bermudagrass
mites, Aceria cynodoniensis, are very small, eight-
legged pests that have caused considerable damage to
bermudagrass lawns in many western areas of Texas.
These cigar-shaped mites can be readily distinguished
from the oval-shaped mites commonly seen around
the home. Females lay eggs in protected places on the
grass. The larval stage, with only six legs, is followed
by a nymphal stage which has eight legs, as do the
adults. The life cycle of this mite is completed in
about a week, and because they can multiply rapidly,
extensive damage can be caused in a short period of
time.
Damage: Bermudagrass mite damage results
from the removal of plant sap from the stems and
leaves, which causes yellow or brown areas and a
generally unhealthy appearance. Characteristic
symptoms of injury are short internodes which cause
the grass to have a bushy or tough appearance. When
mite damage is severe, the grass is severely thin, and
weeds usually take the place of the dead grass.
~anksgrass Mite
Description and Life History: The banksgrass
mite, Oligonychus pratensis (Banks), has been a
problem in the West and High Plains areas of Texas.
This mite is oval and very similar to the two-spotted
mite. Chemical control of this species has been
difficult because of its high level of resistance to
rciticides. Eggs are transparent in color and hatch in I
to 2 days. Approximately 7 to 14 days are required
for completion of a life cycle. The banksgrass mite
may infest grasses and many ornamental plants.
Damage: Plant injury is similar to that caused
by the two-spotted spider mite.
Chiggers, Jiggers and Redbugs
Many people are not aware that the common
"redbug" or chigger is actually amite. The larval
stage of this mite feeds on the skin of man and
domestic animals, rather than on plants, and causes a
severe itching sensation. These mites are members of
the family Trombidiidae and are discussed in detail in
another publication.
Spider Mites on Vegetables
The two-spotted mites usually are quite a
problem on vegetables produced in the home garden,
especially during periods of hot, dry weather. Plants
severely attacked include tomatoes, eggplants, beans
and corn.
Damage: Mites pierce leaf tissue and suck plant
sap in the larval, nymphal and adult stages. Plants
begin to lose color, fading from green to yellow, and
eventually turning reddish. Heavy infestations can
completely kill plants such as tomatoes. The under-
sides of plant leaves should be checked carefully and
frequently for developing mite infestations.
Mite Control
Chemical controls for mites in the home garden
are suggested in Table 1, and a list of miticides that
can be applied to the home landscape is given in
Table 2. Mite control is often difficult because of
resistance to the miticides being used. The home-
owner must be sure to achieve complete spray
coverage of infested plants. Most of the miticides are
contact materials, and the spray solution must come
in contact with the mites to achieve satisfactory
control. Repeat applications (two to four) are
generally required for satisfactory control. Frequent
plant inspection is the best means of determining the
need for additional applications. Read all label
directions carefully before using a miticide material.
Store all unused materials in a locked area to avoid
accidental poisoning of small children or pets.
Table 1. Suggested miticides for the home garden and days from last spray application to harvest.
• 00 not use; not an Environmental Protection Agency registered use.
Oiazinon
Beans
Beets
Cantaloupes
Carrots
Corn
Cucumbers
Mustard greens
3 days
10 days
None
(pre plant or
transplant only I
Kelthane Malathion Sulfur Ethion
7 days l 1 day odays 2 days2
4 days3
10 days4
odays
odays
odays
5 days odays 50 days5
(field)
1 day No preharvest
interval
Okra
Peanuts
Peas
Peppers
Potatoes
Squash
Tomatoes 1 day
Watermelons
1 day
7 days odays
3 days
2 days6 odays7
(0.5Ib/acrel
21 days
(1.0Ib/acrel
odays
2 days8 odays No preharvest
interval
(summer)
2 days9 5 days10 odays 2 days12
1 day 11 28 days13
2 days14 odays
lPreharvest interval through 0.6 Ib/A spray or 1.5 Ib/A dust (beans-45 day preharvest interval from 0.6 through
0.81b/A spray as a foliage application on dry beans only).
20.5 Ib/A spray or 0.81b/A dust.
31.0 Ib/A spray or 1.61b/A dust.
41.5 IblA-Do not make more than one application after the edible parts have formed.
500 not apply more than once after ears have formed.
6Preharvest interval through 0.81b/A spray or 1.5 Ib/A dust-foliage application.
700 not apply more than three times during fruiting period (applicable to the 1.0 lb. rate).
8Preharvest interval through 0.6 Ib/A spray or 1.5 Ib/A dust.
9preharvest interval through 0.81b/A spray or 1.5 Ib/A dust-foliage application.
l03.51b/A as a dust or diluted spray.
112.0 Ib/A as a dust or diluted spray; 0.61b/A as an undiluted (low volume) spray.
120.5 Ib/A spray or 0.8 Ib/A dust.
131.2Ib/A-Do not apply more than once after fruit begins to form.
14Preharvest interval through 0.61b/A spray or 1.5 Ib/A dust.
Table 2. Suggested miticides for the home landscape.
C)
...
~
'N cc c C) 0 c
.! 0 c :.c c
.2c ca ~(5 'N ~ ... ::J 0 ~... ca :!: :.c ...:c ca 1) on;c ~ ::J ...
.;:
U ~ en w I-
Bermudagrass XXXXX
House plants X X
Roses XXXX X
Ornamental citrus XXX X
Woody shrubs XX X X
Marigolds X X XX
Pecans XXXX
Spring flowering annuals XXXX X
Summer flowering annuals X X X X
Follow label directions carefully for rates of applica-
tion.
Table 3. Dilution chart for hand sprayers for homeowner use.
Diazinon
Dicofal (Kelthane)
Malathion
Sulfur
Ethion
Chlorbenzilate
Trithion
%
Emulsion
25
18.5
50
Tsp./Gal.
Water
2
2
2
% Wettable
Powder
100
25
50
25
Tsp./Gal.
Water
9
6
8
6
Use about 1 quint of spray or 1.5 oz. of dust per 50 feet of row.
Educational programs conducted by the Texas Agricultural Extension Service serve people ofall ages regardless of socio-economic
levels, race, color, sex, religion or national origin.
Cooperative Extension Work in Agriculture and Home Economics, The Texas A&M University System and the United States
Department of Agriculture cooperating. Distribu ted in furtherance of the Acts of Congress of May 8, 1914, as amended, and June
30, 1914.
7%.M-5-74 LH3


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Spider Mites in the Home Garden and Landscape.

Abstract

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Texas A&M Repository

Texas A&M University

Spider Mites in the Home Garden and Landscape.

Abstract

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Full text

Available Versions

Texas A&amp;M Repository

Texas A&M University

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