Grapevine Phylloxera in Northern California

Grapevine phylloxera, which threatened to devastate the European wine industry in the mid-19th century, remains a serious threat to vineyards. Hearty American rootstocks were successfully grafted to European varieties to control the devastation. However, the “survival of the fittest” rule ensures that each surviving phylloxera population will be more adaptable to new host plants. After a description of this insect’s taxonomy and morphology, the complicated reproductive strategy will be detailed. Then, following a brief review of the phylloxera in viticulture history, this article will discuss (1) the relationship between the insect and the Vinis species hosts, (2) recent attacks on Napa and Sonoma County vineyards, and (3) associated pest control measures, as well as economic impact. 

Viteus vitifoliae, also known as Dakulosphaira vitifoliae or Phylloxera vitifoliae, is found in the order Hemiptera, suborder Homoptera, superfamily Aphididae, and family Phylloxeridae. There are species of phylloxera specific to oak and pecan trees as well. This report will concentrate on the phylloxera whose entire life cycle is confined to Vitis species hosts. For ease of reading, this paper will refer to the insect as V. vitifoliae or simply phylloxera. The aerial leaf-feeding form of this insect is called gallicolae, and the root-feeding form is called radicicolae. V. vitifoliae may resemble to scale insects to those outside the entomology world, but are closer in morphology to aphids. They hold their wings horizontally when at rest, however, and lack an aphid’s cornicles. Adults are pear or oval-shaped, minute (less than 1 mm), and may be winged or wingless. Color ranges from yellowish green to brown.