Insects and related arthropods are the most commonly intercepted pests, largely because their size, movement, and types of damage they cause make them easiest to detect. Most pathogens are microscopic and difficult to detect unless disease symptoms are apparent. The tabulated data are a direct record of the numbers of different pest types intercepted by port inspectors. The pests intercepted represent an unknown proportion of those actually carried in shipments. Furthermore, the crops listed in the table are hosts for pests that accompany commodities not listed, and many destructive pests may accompany nonagricultural shipments.
Databases are also available.