WVU Update
Summer 2015
Published as a Special Insert for Farm Bureau News
Managing Colorado potato beetle
T
he Colorado potato beetle, Leptinotarsa decemlineata, is a serious
insect pest of several vegetable crops in the family Solanaceae.
Plants commonly attacked by this insect include potato,
eggplant, tomato and pepper. Both the larval and adult
stages feed on the leaves of plants, and if left unmanaged
can quickly cause extensive defoliation. Under heavy
infestations feeding damage to above ground fruit may
also occur.
Description
Adult Colorado potato beetles are
approximately 3/8 inch long and oval
in shape. They have yellowish-white
wing covers (elytra) marked with ten
longitudinal black stripes (five on each
wing cover). Larvae are red to pinkish
in color with two rows of black spots
on each side of the body.
Lifecycle
In West Virginia, this insect typically
has two generations per year. Adults
spend the winter in the soil or under
crop residues and other organic
debris. Adults become active in the
spring (around May) and begin laying
clusters of yellowish orange eggs on
the undersides of leaves. After egg
hatch, larvae feed for approximately
two to four weeks before dropping
to the ground to pupate in the soil.
New adults typically emerge from
the soil one week later to continue
the next generation.
Chemical Control
Neonicotinoid insecticides (e.g.,
imidacloprid) applied at planting
has been the traditional method used
by many West Virginians to control
Colorado potato beetle. However,
the effectiveness of these insecticides
has been waning in some parts of
the U.S. due to resistance.
This insect has a long history of
developing resistance to a number
of the insecticide classes. For
instance, carbamate (e.g., carbaryl)
and pyrethriod (e.g., permethrin)
insecticides are now largely ineffective
for controlling beetles. Rotating
insecticides with different modes
of action is essential for preventing,
or at least delaying, the development
of insecticide resistance. The spinosyn
(e.g., spinosad, spinetoram) and
diamide (e.g., chlorantraniliprole,
cyantraniliprole) class of insecticides,
as well as the active ingredients
novaluron and abamectin, can
be effective insecticide options
for rotation.
Non-chemical Control
Non-chemical methods for
management are also important.
Selecting early-maturing cultivars
and planting later in the season (June)
may allow the harvest of crops before
significant damage occurs.
If practiced on a regular basis, hand
removal can be an effective method
for controlling Colorado potato beetle
in small plantings.
The larvae and adults can be removed
and placed in a container filled with
water and a few drops of dish soap.
The dish soap breaks the water’s
surface tension so the insects sink
into the water and drown rather
than escape.
Another non-chemical method
involves the use of a spring trap
crop planted a few weeks before the
main crop to divert overwintering
beetle populations. These trap crops
– continued on page iii –
Insert provided by WVU Extension Service and Davis College of Ag., Natural Resources, and Design
Summer 2015
West Virginia Farm Bureau News 17