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HABITAT
The Colorado potato beetle originally fed on the buffalo-bur,
Solanum rostratum, a wild plant that is a close relative of the cultivated potato, Solanum
tuberosum. The beetle was originally limited to Central and North America,
particularly the Rocky Mountains of Colorado. But when pioneer farmers introduced the
potato during the 1850s, they presented the beetle with a new and apparently unlimited
food source.
The first infestations were recorded in Nebraska in 1859. During
the next 13 years the beetle moved east across the United States at a rate of 85 miles a
year until it reached the Atlantic coast.
By 1870 the Colorado potato beetle had appeared in
several places in Germany, and within seven years it was a serious pest in German potato
fields. By the late 1920s this beetle was devastating crops throughout continental Europe
and moving eastward into Asia. Today it is found virtually everywhere in the world, except
on some islands such as Great Britain, where it has been suppressed.
Above: The hardy Colorado potato
beetle has survived the many attempts to destroy it.
ENEMIES
Humans are the main enemies of the Colorado potato
beetle. Although insecticides kill thousands of potato beetles, little damage has been
done to the overall population of this resilient insect. The beetle breeds too rapidly and
profusely to be eradicated by any known chemical method.
Another major threat to the Colorado potato beetle comes from the
predatory Carabus beetles, which devour both adults and young. These large ground
beetles are one of the best defenses against infestation by Colorado potato beetles. But
they may be killed by the insecticides intended for their prey. |
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The Colorado potato beetle has
been attacked with every variety of insecticide. Yet this hardy insect still flourishes
and remains a major pest in potato fields throughout the world.
LIFECYCLE
The prolific breeding rate of the Colorado potato beetle is the
key to its success. Each female may lay up to 2,500 eggs in batches of 20 to 80, attaching
them to the undersides of potato leaves to protect them from the rain and sun. These eggs
hatch within 10 to 14 days. The larvae start eating at once, soon stripping a plant of
leaves.
Within two to three weeks each larva is fully grown and
retires underground to pupate. After 10 to 15 days it emerges as a mature beetle, ready to
start breeding. In a warm summer there may be three generations of larvae, and the
potential for population growth is immense. One beetle hatching in spring may have many
thousands of descendants by fall, each capable of breeding at the same rapid rate.
In winter the mature beetle tunnels deep in the soil to
hibernate. It can survive freezing conditions this way, emerging late the following spring
to assault the new potato crops.
Above: The beetle eats just the leaves
of the potato plant, but that is enough to destroy the crop.
Since
its discovery in the nineteenth century, the infamous Colorado potato beetle has spread to
almost every country where potatoes are cultivated. Feeding on the leaves of the crop, the
beetle multiplies to plague proportions-- and it may ultimately destroy its own food
supply because of the sheer magnitude of its numbers. |
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FOOD & FEEDING
The Colorado potato beetle and its larvae feed on the leaves of
the potato plant, using their powerful jaws to slice through the leaves at an amazing
rate. A few insects can rapidly strip a plant of its leaves, and a thriving population can
easily ravage a whole field. The potato tubers are not touched because they are
underground. But once the plants have lost their foliage, the tubers stop growing, and the
crop is ruined as a result.
Although the Colorado potato beetle prefers to eat
potatoes, it will feed on related plants such as nightshades, tomatoes, and buffalo-burs.
These plants are all members of the family Solanaceae, and they have highly toxic
alkaloids (compounds containing nitrogen) in their foliage. But these poisons seem to have
no effect on the Colorado potato beetle.
KEY FACTS
Length: Adult, 1/10-1/2 in. Larva,
1/2 in.
Coloration: Adult, bright yellow with black
stripes on wing covers. Larva, deep pink with black spots when hatched, then yellow with
black markings.
Breeding season: Late spring to late summer.
Number of eggs: Up to 2,500, laid in batches of
20-80.
Hatching time: 10-14 days.
Habit: Larvae feed in broods, but adult is
basically solitary.
Diet: Foliage of potato and other plants of the
nightshade family. Lifespan: 1-2 years.
RELATED SPECIES
The Colorado potato beetle is one of the leaf beetles, which also
include the elm leaf beetle, striped cucumber beetle, and flea beetles. |
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Did You Know?
The Colorado potato beetle can survive both scorching summers and
arctic winters.
If alarmed, a Colorado potato beetle will lie on its back with its
legs and antennae retracted to fake death.
When it was discovered in 1824 The Colorado potato beetle was
considered a very attractive rarity.
In Great Britain, people are required to report any potato beetle
they find to the police. Thery are asked to bring a specimen and note its location,
because prompt action could prevent and outbreak. |
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