Dead striped flea
beetle on soil;
note faded color
of pronotum
4/2012
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Pale-Striped Flea Beetles in Young Cotton Stands Peter C. Ellsworth and Lydia Brown
Pale-Striped Flea Beetles, Systena blanda, are small (3/16
inch) beetles that invade cotton early in the season. Adults
Striped flea beetle
bear brown & white longitudinal stripes & jump when
on damaged
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disturbed. They feed on cotyledons early on & lower leaves
cotyledon
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Stripe Flea Beetle
on Cotton
later in the season. Their chewing mouthparts score the upper
Damage
Rating
=
1
(most often) & lower surfaces of leaves without causing
holes. Wounds bleed sap & scarred tissues turn brown. Flea
beetles rarely attack true leaves while cotyledons are present
& attractive. Damage is largely cosmetic & often limited to
Other flea
field edges, though remedial action (incl. advanced
beetle species
irrigations) may be needed when the water-balance of a
may also be
young stand is jeopardized.
present, but
Stripe
Flea
typically
do Beetle
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Decisions on control actions or advancing irrigations to
Feeding
not cause
scars
mitigate flea beetle damage require attention to many factors.
economic
Most critical is plant development. If severe damage occurs in
damage
Swollen femur found in
the hours after cotyledons emerge, the stand may be
all flea beetle species
Stripe Flea Beetle Dam
jeopardized and action justified. However, more often,
Damage Rating = 2
Damage Rating = 3
damage occurs slowly as the plant develops. As long as there
First
are not other complicating factors that weaken the stand
true leaf
(injury from thrips, disease, etc., but especially poor water
relations or suboptimal soil temperatures), the vast majority
of stands outgrow this damage without penalty of yield or
loss of time. Generally, emergence of the first true leaf
signifies safety of the stand. Nevertheless, scarring can be
First
Old (tan)
Fresh
dramatic, and under poor growing conditions controls may be
true leaf
scars
(green)
required.
scars
Other factors to consider are location in the field and seed
Severe striped flea beetle damage;
first true leaf insufficiently
developed;
treatments. Infestations tend to be spotty, favoring field
Damage
Rating 2
loss of plant likely
borders, edges, and nearby drying weedy habitat. In these
Damage Rating 2
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cases, spot treatments with insecticides may be effective.
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Also, many neonicotinoid seed treatments provide protection
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to cotyledons so that a foliar spray is generally unnecessary.
Flea beetles may still do some minor feeding despite the seed
Attached
seed coat
treatment. They will normally hop when approached; more
sluggish movements indicate effects of seed treatment. Foliar
sprays, including broad-spectrum insecticides and
neonicotinoids, provide sufficient control. Take great care in
early season uses of insecticides, as secondary pest
outbreaks can result (esp. mites) and the benefits in yield
or timeliness are not proven under normal growing
conditions in AZ. Beneficial arthropods colonize the field
Damage Rating 3
early in the season and set the stage for a season full of
natural controls of many primary and secondary pests. Under
Damage Rating 3
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Striped flea beetle and the damage this species causes,
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including different damage ratings (1–3, with 3 the most
development and soil water profile, coming back early with$
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severe). Damage rating
of 3 without active development
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of the first true leaf
can lead to plant death and, if
an irrigation on a field edge or small area may be$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
needed
to
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widespread, to stand loss. However, once the first true
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quicken plant development and avoid stand loss.
leaf is developing, the plant is generally safe from any
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Any products, services, or organizations that are mentioned, shown, or indirectly
implied in this publication do not imply endorsement by the University of Arizona.
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loss of yield or timeliness
in plant development. Photos:
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Peter C. Ellsworth © 2012, University of Arizona
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