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How to Manage Pests:
Pest Management and Identification
Vedalia beetle
Scientific name: Rodolia cardinalis
Click on image to enlarge
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Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Coccinellidae
Common prey: Predaceous exclusively on cottony cushion scale in
citrus and
ornamentals
Commercially available: No
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DESCRIPTION
Lady beetles are easily recognized by their shiny,
convex, half-dome shape and short, clubbed antennae. Most lady beetles,
including this species, are predaceous as both larvae and adults. Young
lady beetle larvae usually pierce and suck the contents from their
prey. Older larvae and adults chew and consume their entire prey. Larvae
are active, elongate, have long legs, and resemble tiny alligators.
Many lady beetles look alike and accurate identification requires a
specialist.
Unless disrupted by pesticide use or other adverse conditions,
the vedalia beetle and the parasitic wasp, Cryptochaetum iceryae, provide
complete biological control of the cottony cushion scale. R.
cardinalis was introduced into California citrus groves in
1888 and saved the citrus industry from destruction by the cottony
cushion scale. Due to its success, the vedalia's introduction is
now viewed as the beginning of classical biological control.
Adult vedalia beetles are small, measuring 2-4 mm (<3/16 inch)
long, and are red and black with a covering of fine hairs which
often gives them a grayish appearance. The larvae are reddish in
color. Red and black pupae develop within the grayish skin of the
last larval instar and occur among or near scale colonies. Oblong,
red eggs are laid singly or in groups on or near cottony cushion
scales. R. cardinalis undergoes complete metamorphosis and
has 8 or more generations per year. Both adults and larvae feed
exclusively the cottony cushion scale on a variety of plants including
rose, acacia, magnolia, olive, and citrus. Adults and mature larvae
feed on all stages of the scale while young larvae feed only on
eggs. The vedalia beetle is extremely sensitive to some pesticides
and care should be used when applying pesticides in areas where
the beetle is relied upon for control of the cottony cushion scale.
More information and photos of vedalia beetle UC
ANR publication 8051 (PDF* 438K)
*Requires Adobe Acrobat Reader version 4 or later. If this software
is not installed on your computer, download a free copy of Acrobat
Reader.
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