Sir

The cover of the issue reporting the landmark genome sequencing of the bacterium Xylella fastidiosa (Nature 406, 151–157; 2000) shows a vector, but we are not told what sort of insect it is. Michael Bevan's accompanying News and Views article (Nature 406, 140; 2000) reveals that the vectors are xylem-feeding leafhoppers, but no names are mentioned.

The culprit is, in fact, a species of Acrogonia, a member of the tribe Proconiini of the subfamily Cicadellinae. All members of this leafhopper subfamily are xylem feeders, and some species in several genera are known or potential vectors of both the citrus disease and Pierce's disease of vines in the southern United States. It is not possible to identify the Acrogonia species from the cover photograph: colleagues in Brazil confirm that it could be an undescribed species. There is much taxonomic work to be completed.

Insect taxonomists are a threatened species worldwide. Have we already reached the situation where more scientists can sequence a genome than can identify the potential vectors? Control measures against Xylella and other similar organisms will depend not only on such advances but also on being able to elucidate the biology of potential vectors once they have been identified by taxonomists.