Annual cicadas (dog-day cicadas)

About

Big, dark cicadas, about 1 1/2 to 2 1/2 inches long with green markings, whose loud buzzing fills mid- to late-summer days. Unlike periodical cicadas (their own page), some come out every summer, and they rarely harm plants (Illinois, NC State).

Spotting it

Damage

Females cut rows of slits into small twigs to lay eggs, and those twig tips may die, brown and break off (flagging). Numbers are usually small, so the damage often goes unnoticed, and nymphs feeding on roots do no noticeable harm (NC State, Ohio State, CSU).

How to find it early

You'll hear them first. In late summer, look for browned, wilted twig tips with rows of small slits on young trees (NC State, Ohio State).

When

Mid to late summer, about July through September.

Life cycle

Eggs hatch in six or seven weeks, and the nymphs drop to the ground and feed on roots for 2 to 10 years, depending on the species. Generations overlap, so some adults come out every summer, leaving exit holes in the soil and papery cast skins on bark (NC State, Illinois, Ohio State).

What to do, gentlest first

Start at the top. Sprays are a last step; always read and follow the product label.

1. Live with them Prevent

   Annual cicadas do little harm to tree health, and NC State says pesticides aren't warranted. Cicada killers, the big ground-nesting wasps that hunt them, are not aggressive and rarely sting (Ohio State).

2. Net young trees only if needed Barrier

   Control rarely works, but netting can keep egg-laying females off young woody plants (UC IPM).

Plants it goes after

Aster, Flowering crabapple, Goldenrod, Oaks (white, red and pin oak), Peach, Persimmon (American and Asian), Red maple, Sugar maple, Thornless honeylocust

Pressure by region

Annual cicadas live across the lower 48: North Carolina has at least 13 Neotibicen species, Colorado 29 cicada species and California at least 65 (NC State, CSU, UC IPM). Damage is minor everywhere, so every region is rated low; the Alaska and Hawaii ratings are estimates.

Ratings come from extension sources where available; some are estimates, as noted above.