Thrips affect vegetable crops in several different ways. Sometimes
their effects can be devastating. Economic damage is often greatest
in the first year or two after a new pest species
is introduce to the area. This damage is due to explosive population
increase in the absence of natural enemies.
The movement of, not only thrips, but other insect
pests as well, is a global phenomenon, which is becoming increasingly
important. Rapid shipment of agricultural commodities, especially
ornamental plants and tropical fruits, facilitate this process.
Even on a statewide basis, the tendency of thrips to be attracted
to light colored surface, such as clothing, presents the possibility
of movement from area to area in motor vehicles. The movement
of western flower thrips from the west
coast of the United States throughout the country and into Europe,
and that of melon thrips throughout the
tropics are prime examples of this. This worldwide spread happened
in a few years in each case.
Of course, insects are perfectly capable of moving into new areas
without the help of humans. The sequence of new detections suggests
that major storm systems, such as hurricanes, may also play a
role in moving insects over long distances. Thrips have been collected
at altitudes of 500-11000 feet, indicating this is a real possibility
(Stannard 1968; Glick 1939, 1960).
The risk of serious economic losses from new pests makes it important
for growers and other agriculturists to be keenly aware of the
exact identity of the pests infesting their crops. The identification keys
andspecies descriptions in this knowledgebase
are designed to meet that purpose. This information may be completely
useless, though, if crops are not scouted by competent, well-trained
personnel. A good crop scout is the best defense against costly
surprises!