'' (right)
G. coccinea has been identified as one of several leafhopper species that is a
vector in leaf scorch caused by the
gammaproteobacteria Xylella fastidiosa ("
Pierce's disease").
X. fastidiosa is responsible for the decline of certain
woody plants such as
elm,
oak, and other
ornamental trees. According to a
research entomologist at the
United States National Arboretum, "An understanding of the transmission of this
bacterium by insect vectors is economically important because there is neither any known effective therapy for infected trees and
shrubs nor a strategy for preventing infection." In California they damage valuable crops and in Germany they are a nuisance to people sitting under trees in public parks. ==Subspecies==