Economic Importance

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!