Anyone who ever has been around potato plants will recognize
a yellow- and black-striped insect known as the Colorado potato beetle. Some
entomologists suggest this might be the best-known beetle in North America.
Sometimes called a potato bug, this beetle has been the bane
of potato farmers and gardeners for more than 100 years. Potato beetles and
their offspring eat the leaves of potato plants, which can be a problem for
farmers and gardeners.
This insect was named the Colorado potato beetle because it
was first identified in Colorado, eats potatoes and is a beetle. North American
entomologist Thomas Say discovered the insect.
Say collected the beetle when he was the zoologist on Major
Stephen H. Long’s 1819-1820 scientific expedition to the Rocky Mountains. He
described the insect in an 1824 report published about the Long
When Say discovered the Colorado potato beetle, the insect
was feeding on a weed called the buffalo bur. Then, some 30 years later, the
early settlers of Colorado introduced potato plants to the area. This Colorado
beetle began using the potato as a food plant.
With a new food plant available, these insects began to
spread eastward. The area where the beetles were found grew by about 85 miles
As they moved, the beetles destroyed most of the potato
plants in their path. By 1874, the Colorado potato beetle had reached the
Anyone who raises potatoes today still is just as likely to
encounter infestations of Colorado potato beetles as were folks a century ago.
And for many gardeners, the approach to control is the same as it was in those
bygone times – handpicking.
Most people aren’t enthralled with the idea of picking
potato beetles or their soft-bodied young off the plants. Such a task generally
was assigned to youngsters in the family, and many remember the job was not a
The beetles spend the winter as adults buried in the soil.
In the spring, the adults emerge and begin to lay eggs on the potato plants.
The orange-yellow eggs are attached in batches to the
underside of the leaves of the plants. The eggs hatch into slug-like young,
which are red-colored with two rows of black spots along each side.
Picking potato bugs might be an ecologically friendly method
for controlling this insect, but it is difficult to achieve good control with
this approach. Consequently, potato growers quickly turned to using insecticides
to deal with this pest.
An inorganic compound called Paris green was used in 1865.
Paris green was so-named because of its green color and its use to kill rats in
the Paris subways.
Lead arsenate also was used as an insecticide against this
beetle. Following World War II, DDT became the insecticide of choice to control
many insects, including the Colorado potato beetle.
Paris green, lead arsenate, DDT and other
chlorinated-hydrocarbon insecticides often were used as a dust formulation. The
insecticide was applied by shaking it through a coarse mesh bag such as one made
Needless to say, this probably was not the safest way to
apply insecticides — this practice was before the Environmental Protection
Agency and pesticide safety rules for farm workers.
Because of the severity of the Colorado potato beetle as a
pest, the insect played a role in the development of the modern pesticide
Hundreds of insecticides have been tested to evaluate
effectiveness for beetle control. Almost all classes of insecticides have been
used against the beetle over the years.
The Colorado potato beetle has responded to the widespread
use of insecticides to kill it by developing resistance to many of the
chemicals. Resistance means that a specific product no longer kills the insect
because of genetic selection.
The beetle had become resistant to DDT in 1952, some 10
years after the chemical was first used for control. Today, the Colorado potato
beetle is resistant to more than 50 different compounds from all classes of
Because Colorado potato beetles are difficult to kill with
most insecticides, I have decided to use an old-fashioned method of control in
my garden. I resort to handpicking the insects off potato plants.
Besides, I get a little bit of sadistic pleasure from
killing an insect that has the audacity to make a meal of the plants in my