The meadow spittlebug, Philaenus spumarius (also formerly distinguished Philaenus leucopthalmus as a separate species), is native to Eurasia but is now common in some regions of North America and New Zealand. Because the adults can vary greatly in color and markings, they have been the object of numerous field studies of its population genetics; consequently, a long list of plants have been listed as hosts from which it was collected. In the 1940s the meadow spittlebug and other spittlebugs were shown to be able to transmit the causal agent of Pierce’s disease of grape (then considered to be viral, now known to be caused by the bacterium Xylella fastidiosa) and also a vector of X. fastidiosa to almond. It has not been considered important in the spread of Pierce’s disease in California.
Philaenus spumarius became an important candidate for the spread of a lethal olive disease first described in extreme southeast Italy in 2013 (PDF). The Olive Quick Decline Syndrome (OQDS) is caused by a strain of X. fastidiosa not noticed until 2013 in declining olive trees. This same strain was soon also detected near declining olive orchards in oleanders and almond trees with leaf scorch symptoms. The adults lay eggs in weeds (perhaps soil too?) in late summer or fall. In the Salento region of Italy, some adults have been observed to survive until the end of winter. In northern California, P. spumarius eggs laid the previous year hatch in late winter and early spring. Some favored plants found in Napa and Sonoma Valleys are prickly ox tongue (Picris ecioides), smooth cat’s ear (Hypochaeris glabra), narrowleafed plantain (Plantago lanceolata), and French broom (Genista monspessulana). Vetch (Vicia sp.), California barley (Hordeum californicum), wild oats (Avena sp.), English ivy (Hedera helix), Mexican bed straw (Gallium mexicanum). The reproductive biology of the meadow spittlebug in California is not known.