These insects (family Cicadidae) are known for the loud, shrill buzz or click sounds males of many species make to attract females. At least 65 species in 8 genera occur in California, including at least 36 Okanagana species and 18 Platypedia species. Unlike in the eastern United States, aside from their sporadic noise making cicadas are generally not pests in California landscapes.
Adult cicadas are robust insects up to 1-1/2 inches long with mostly clear wings. They are commonly blackish or dark brown, although some species have green, orange, or red markings. To help discriminate between types (families) of insects with similar-looking adults see Distinguishing Among Sucking Insects That Resemble Each Other. See CalPhotos for more pictures of more cicada adults and nymphs.
Eggs are narrow, whitish, and several times longer than they are wide. Eggs occur in groups hidden in twig bark. Where oviposition occurred bark can appear punctured or repeatedly cut into with a blade. Nymphs occur hidden in soil where they feed on roots. They are pale and stout and appear hunchbacked.
Cicadas develop through three life stages: egg, nymph, and adult. Adult females lay eggs in tender bark of twigs, commonly twigs about the diameter of a pencil. The hatching nymphs drop to the ground and use their enlarged clawlike forelegs to burrow into soil. Each nymph sucks and feeds on the xylem fluid of roots for several years as it develops through about five increasingly larger instars. The mature last instar then emerges from underground, climbs an object, sheds its skin, and becomes an adult. Adults seek mates and the mated females lay their eggs. One generation commonly requires several years with almost the entire life span spent as nymphs feeding underground.
The loud, shrill buzz and click of male cicadas can be annoying. But each male lives only a few weeks and those of a species commonly all emerge and die during roughly the same time. Females can cause terminal dieback where their insertion of eggs into woody shoots girdles the stem, killing twigs and small branches. However, reports of cicada damage are uncommon in California.
Predators of cicadas include birds, moles, other vertebrates, predaceous wasps (e.g., family Sphecidae), and spiders. However, it's believed that natural enemies generally have little effect on cicada populations in part because most of their life cycle is spent in soil where nymphs can occur on roots as deeply as two feet below the surface.
Except for preventatively netting young woody plants to exclude insects, cicada control efforts generally are not effective. Within a few weeks after they emerge, the relatively short-lived adults will die. In California, these noisy insects generally are not pests and do not warrant control efforts.
For more information see The Cicadas of California Homoptera: Cicadidae and The Ecology, Behavior, and Evolution of Periodical Cicadas .
Adapted from the publications above and Pests of Landscape Trees and Shrubs: An Integrated Pest Management Guide, University of California Statewide Integrated Pest Management Program (UC IPM).
Twig injury from cicada egg laying.
Adult of cicada.
Nymph of cicada.
Cast skin of last instar (nymph) of cicada.