Small Grain Pests
Aphids
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Order Homoptera
Family Aphididae
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corn leaf aphid and English
grain aphid are common aphid pests on small grains in PA.
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Description:corn leaf aphids are
blue-green with dark spots around the cornicles. Legs and cornicles are
black
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English grain aphids have
yellow-green body with black antennae and cornicles
Aphids
General Life History of Aphids
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Aphids have a complex life cycle
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Most overwinter as eggs
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Females hatch from eggs in
spring
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Females reproduce
parthenogenetically, giving birth to live aphids.
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Several generations per season
may be produced this way
General Life History of Aphids
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Eventually some winged progeny
are produced
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Winged aphids often migrate to
different plant hosts
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Eventually a generation of both
males and females are produced
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These aphids mate, and the
females lay eggs
Aphid Damage
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Corn leaf aphids and English
grain aphids are vectors of barley yellow dwarf virus
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The virus causes plants to turn
yellowish and stunts growth
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Aphids can also suck sap from
plants and leave brown blotches on the plant
Aphid Damage
Aphid Management
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During the fall, populations of 25 aphids per foot of row
is the threshold for treatment. During the spring, populations exceeding 100
per foot of row are needed before treatment is warranted
Armyworm
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Order: Lepidoptera
Family: Noctuidae
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Pseudaletia unipuncta
Armyworm Damage
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Chew on leaves of small grains
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Sometimes cut off the heads of
grain
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Cause more damage to barley than
wheat
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Armyworms do not cause damage in
fields containing only alfalfa or other legumes (this is generally cutworm
damage)
Armyworm Damage
Armyworm Management
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Six or more worms per linear
foot of drill row is the threshold for treatment
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Control of pest might not be
recognized immediately after spraying due to the habits of the insect
Cereal Leaf Beetle
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Order Coleoptera
Family Chrysomelidae
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Oulema melanopus
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Origin: Europe, Middle East,
North Africa
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U.S. Distribution: Eastern U.S.
and southern Canada
Cereal Leaf Beetle
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Adults approx 4mm long.
Black-blue head and elytra. Rest of body is red
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Larvae are yellow with a black
head capsule
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Eggs yellow (darken towards time
of hatching)
Cereal Leaf Beetle
Cereal Leaf Beetle Life History
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Adults overwinter in plant
debris on field ground
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feed on wild grasses in early
spring
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move to grain fields later in
spring and females lay eggs
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Larval feeding lasts 10 days
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Pupate in soil (below 50mm)
Cereal Leaf Beetle Life History
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Adults emerge in summer and feed
a little
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Adults aestivate until fall, at
which point they search out a suitable spot to overwinter
Cereal Leaf Beetle Damage
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Adults and larvae feed on the
upper leaf surface of young oats
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Both feed on the flag leaf or
new growth of winter wheat (larvae are window feeders)
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Tips of damaged leaves turn
white
Cereal Leaf Beetle Damage
Cereal Leaf Beetle Management
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Parasitic wasps (5 species) were
released by USDA to control outbreaks of CLB
Cereal Leaf Beetle
Hessian Fly
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Order Diptera
Family Cecidomyiidae
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Mayetiola destructor
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Origin: Europe
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Distribution: wheat producing
areas of the world
Hessian Fly
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Adults: approx 2.5 mm long,
black, look like a mosquito. Gravid females have a red abdomen
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Young larvae are red, but older
larvae are white. Green stripe runs longitudinally along the dorsum
Hessian Fly
Hessian Fly Life History
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Larvae overwinter on plant
debris
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Pupation occurs in early spring
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Adults emerge between 2 and 3
weeks after pupation
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Adults mate and lay eggs (live
only 2-3 days) in the grooves of wheat leaves
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Larvae feed in early summer,
pupate in late summer
Hessian Fly Life History
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Adults emerge in fall and lay
eggs
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Larvae feed for a short time in
fall and then overwinter in puparia
Hessian Fly Damage
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Larvae feed between leaf sheath
and stalk, resulting in stunted growth and weakened plants
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A single larva can cause
significant damage to a wheat plant because of the salivary toxins released
while feeding. These toxins interfere with normal wheat growth
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One leaf stage plants are often
killed
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Wheat attacked later may be
stunted
Hessian Fly Damage
Hessian Fly Management
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Cultural
practices can help to reduce population numbers, esp. destruction of
volunteer wheat
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Delayed
planting
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Use
of resistant wheat varieties
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Insecticides
are rarely recommended because of the sporadic nature of severe Hessian fly
infestations
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Two
parasitic wasps are natural enemies of the Hessian fly
Hessian Fly Management
Grasshoppers
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Order Orthoptera
Family Acrididae
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Description: (differential
grasshopper)1.5 to 1.75 inches long, yellowish with brown and black markings
and black markings on hind legs
Grasshopper
Grasshopper Life History
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Overwinter as eggs
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hatch in early spring (after
adequate rainfall is received)
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nymphs move to areas of
plentiful food resources
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Adults appear after 5 to 6
nymphal molts
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Adults mate and females lay eggs
Grasshopper Damage
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Feed on outer edges of leaves
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Attack all types of field crops
Grasshopper Management
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Grasshoppers have multiple
natural enemies, including flesh flies, bee flies, blister and ground
beetles, spiders
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Tilling the soil can kill
grasshoppers in the egg stage