Answers to some common questions about periodical cicadas
When will the periodical cicadas appear in my area?
The next emergence (17-year Brood II) will emerge from April to June of 2013. See the brood maps for other upcoming emergences. Even if the maps suggest that cicadas are going to emerge be in your area, remember that cicada populations are patchy, so they may be in woods nearby, but not at your house, etc.
When do the cicadas start to come out?
In the springtime -- late April or May in the warmer states and May or early June in the cooler states. (The nonperiodical "annual cicada" species emerge from late June into late summer).
When exactly do they start to come out? (i.e., I'm planning a wedding in May! Help!)
See the Cicada Wedding Guide at Cicada Mania.
How long will the cicadas be out in my yard/neighborhood/city?
About 4-6 weeks after they first start emerging. Most individual cicadas live only a few weeks, but since they emerge over a period of two weeks or so the whole event lasts longer. The serious noise will get going about a week and half after you first notice them and will last about two weeks more. After that things get a lot quieter.
How do I tell the species apart?
There are currently 7 described Magicicada species. You can see their characteristics by visiting the species pages on this site, where you will find photographs, sounds, and distribution maps. The -decim species differ in abdomen color. M. neotredecim and M. septendecim tend to be darker than M. tredecim.
This link takes you to an illustrated table showing typical species abdomen color differences.
This link takes you to an illustrated map of song displacement among the M. decim species.
Will cicadas chew up my plants?
No, cicadas do not chew -- they have no chewing mouthparts, and they feed (drink, really) more like aphids. Adult and nymphal cicadas feed on plant sap called xylem fluid - the watery part of the plant sap - which they suck up through their proboscis (feeding tube). Feeding by periodical cicadas does not seem to affect trees and shrubs very much because they take only a small fraction of the water passing through.
Will cicadas hurt my perennials/annuals?
Probably not, cicadas have little interest in these plants (except if any are woody). You may see teneral (newly emerged) cicadas sitting on such plants, or emerging on them, but they will soon move up into the trees.
Will cicadas hurt my young trees?
Possibly. Adult cicadas singing and flying and feeding on young trees are very unlikely to do any damage. However, females do pierce/cut small branches on woody plants to insert their eggs, and if too many cicadas do this the branches may weaken, die and/or break off. The best way to prevent this is to cover such young plants with bird netting (see below) or cheesecloth, but before going to this trouble wait until you see how many cicadas are out in your immediate area (female cicadas will not begin laying eggs until at least one week after they first emerge, so there is no hurry). Cicadas do not usually move more than a few hundred meters to lay their eggs.
Can the cicadas hurt me?
No. Cicadas don't bite or sting defensively, and they are not toxic or poisonous.
I saw lots of cicadas emerge but they all disappeared and I can't hear any singing -- where did they go?
Newly emerged cicadas (teneral cicadas) take about five days of good weather before the males start singing. Tenerals move higher into the trees when they have hardened enough to climb. Many of the early-emerging cicadas are eaten by birds as well-look for discarded wings on the ground under the trees.
I hear a loud repetitive noise at night, is this cicadas singing?
No, there are no cicadas in the U.S. that sing at night. When Magicicada populations are very dense, some individuals may utter short bursts of sound during unusually hot nights, but this behavior is not typical. Most noises at night are crickets, katydids, or frogs.
Can cicadas see (i.e., did it have to land on me)?
Yes, cicadas have very good vision. They have five eyes (two large red compound eyes on the sides of the head, and three small ocelli (simple eyes) located in a triangle on the front of the head). Periodical cicadas simply don't much care what they land on, since in natural circumstances everything they land on is a tree; don't take it personally when periodical cicadas land on your head/pet/car etc. Even the nymphs can see when they emerge from their burrows to metamorphose - they can head towards a tree (or your leg!) - anything vertical - in the near-darkness from many meters away.
How loud are periodical cicadas?
This is not an easy question to answer, since it depends where you are - even a 747 taking off sounds quiet if you are a mile away! Some of the louder choruses reach 90+ decibels as perceived while standing under the tree. Individual periodical cicadas are actually not that loud as cicadas go.
Why do I hear cicadas every year?
There are 150 or so species of cicada in the U.S. (including species of Okanagana, Diceroprocta, Cicadetta, Neocicada, Cacama, Okanagodes, Magicicada and other genera). Only the seven Magicicada species have synchronized development and periodical emergences (meaning that all individuals in a population are always the same age). The rest of the species (the so-called annual cicadas) have unsynchronized development, so some individuals mature in every year and we hear them every summer.
What's the best terminology for talking aboout them?
Cicadas do not “swarm", "invade", or "overrun" (if they emerge aboveground, they have been there the whole time, just underground), nor are they a “plague" (Biblical plague locusts were grasshoppers). Cicadas do not hatch out of the ground (they hatched from eggs in tree branches 17 years ago), and they do not "hibernate" (they are undgerground actively feeding). When they moult to become adults, the correct term for that process is "ecdysis."
What purpose do they serve?
This question is tough to answer from a scientific point of view because biologists explain organisms as products of natural selection, the evolutionary process in which traits that increase reproductive success tend to be preserved in future generations. However, in biology we do examine the effects that cicadas and other species have on each other and on their environment, and this is related to what people often have in mind when they ask about the purpose of a given species. Periodical cicadas are exploited as a food source by a wide variety of species, but only underground or microsymbiotic organisms can evolve to specialize on them since they appear aboveground so rarely. The tunnels of nymphal cicadas aerate the soil and presumably influence soil ecology and tree growth. The twig damage caused by female oviposition actually acts like a pruning for some trees, stimulating future growth. For many people, periodical cicadas are a marvel of nature, a source of many intriguing evolutionary puzzles; or, for some, just a nuisance.