The biology and ecology of armored scales.

The armored scales (Family Diaspididae) constitute one of the most successful groups of plant-parasitic arthropods and include some of the most damaging and refractory pests of perennial crops and ornamentals. The Diaspididae is the largest and most specialized of the dozen or so currently recognized families which compose the superfamily Coccoidea. A recent world catalog ( 19) lists 338 valid genera and approximately 1700 species of armored scales. Although the diaspidids have been more intensively studied than any other group of coccids, probably no more than half of the existing forms have been recognized and named. Armored scales occur virtually everywhere perennial vascular plants are found, although a few of the most isolated oceanic islands (e.g. the Hawaiian group) apparently have no endemic representatives and are populated entirely by recent adventives. In general. the greatest numbers and diversity of genera and species occur in the tropics. subtropics. and warmer portions of the temperate zones. With the exclusion of the so-called palm scales (Phoenicococcus. Halimococcus. and their allies) which most coccid taxonomists now place elsewhere ( 19. 26. 99). the armored scale insects are a biologically and morphologically distinct and homogenous group. The definition of subfamily and tribal categories within the Diaspididae is a matter of some disagreement among taxonomists. although most recognize at least four major subdivisions: the aspidiotines. diaspidines. parlatorines. and odonaspidines. Borchsenius (19) treated these as subfamilies, whereas earlier workers (8) gave them tribal status within the nominate subfamily of a more inclu­ sive family Diaspididae. Recently Takagi (99) has proposed dividing the Diaspididae into seven tribes (the larger number derived by splitting Balachowsky's Diaspidini and Parlatorini). without designating subfamilies. Takagi's scheme. which is based