Technical Abstract: Almond leaf scorch (ALS) is caused by the bacterium Xylella fastidiosa which is transmitted by xylem-feeding sharpshooters and spittlebugs. Reports of increased incidence of ALS-affected almonds in California prompted surveys in three almond-growing regions in California, from June 2003 to September 2005, to determine insect vector species composition and abundance. For comparison, sampling in and near vineyards in the San Joaquin Valley was also completed. More than 42,000 Cicadomorpha were collected, of which 4.8 percent were xylem-feeders, including 1,912 Draeculacephala minerva Ball, five Xyphon fulgida Nottingham, and a single spittlebug (Philaenus spumarius L.). The dominant vector, D. minerva, was more frequently collected in the Sacramento Valley than in the San Joaquin Valley. Season-long sampling indicated that D. minerva was a year-round resident in and/or near almonds in the Sacramento Valley, but not in the San Joaquin Valley. Similarly, D. minerva was rare in vineyards in the San Joaquin Valley, but was abundant in irrigated pastures near vineyards. Draeculacephala minerva was most frequently collected along orchard margins. Peak densities of D. Minerva were observed in summer, the period of time when bacterial titers begin to increase in infected trees. Screening of D. minerva for presence of X. fastidiosa found that 1.1 percent tested positive. All X. fastidiosa-positive D. minerva were collected from inside almond orchards and all carried pathogen strains that matched those collected from ALS-affected almond trees in the same orchard. Of the few X. fulgida and P. spumarius collected, none tested positive for X. fastidiosa.