Resources & FAQs

Yes, but those are our “annual” cicadas which differ in their appearance and biology.  The commonest “annual” cicadas that we see each year are commonly known as “dog-day cicadas”, since the adults are active during the hot “dog days” of summer. These have life cycles lasting 2-3+ years, but with overlapping generations some adults emerge every year. The mass emergence that the Midwest will see this year involves a different type of cicada—the “periodical” cicadas. These are referred to as periodical cicadas since they have long life cycles and periodically emerge in huge numbers. We technically have 7 different species of periodical cicadas in North America—3 species that have 17-year cycles and 4 species with 13-year life cycles.  In total there are 15 different broods of periodical cicadas.

See the Cicada Basics page for more details about our “dog-day” and “periodical” cicadas.

Scientists sort periodical cicadas into numbered broods (cohorts) based on when they emerge; the broods are numbered with Roman numerals. Early efforts to categorize these cicadas into broods date back to the roughly 200 years, but the currently accepted categorization method was developed by C.L. Marlatt in the 1890’s.

This year is unique in that two groups (broods) of periodical cicadas are emerging: Brood XIII (The Northern Illinois Brood) 17-year cicadas and Brood XIX (The Great Southern Brood) 13-year cicadas.  The two broods are separated geographically, but overlap slightly in central Illinois.

Adult periodical cicadas large, robust insects with four membranous wings possess that are held roof-like over the body at rest.  The head is thick with a prominent red eyes and a bulging, “radiator-like” structure (frons) on the front of the “face”.  Their bodies are black with orange on the legs and the wings.  The nymphs (juveniles) have a very different appearance.

See the Cicada Basics page for more detailed descriptions and photographs.

To track the geographic distribution of periodical cicadas, early survey efforts relied on government-organized mail-in surveys.  Additional activity has also been recorded in newspapers and annual reports by universities and government agencies.  Research scientists have also historically visited sites in search of these insects.

In more recent times, citizen/community science projects have helped gather additional data about the timing and distribution of cicadas.  This year, a project has been launched by UW to help develop a better picture of the periodical cicada distribution in Wisconsin (see the Share Your Sightings page to participate).

There are currently 15 existing broods of periodical cicadas—12 broods with 17-year life cycles and 3 broods with 13-year life cycles.  There are two additional broods that were documented historically, but are believed to have gone extinct.

Only one. While states like Illinois, Virginia, and Pennsylvania see many different broods of periodical cicadas, in Wisconsin we only have Brood XIII (17-year) cicadas.

Brood XIII cicadas emerged most recently in 2007 and will emerge again this year (2024). Previously this brood emerged in 1990, 1973, 1956, 1939, 1922, 1888, and 1871, with some early records dating back to 1854 in the state (a mere 6 years after Wisconsin gained statehood).  Undoubtedly, this brood existed prior to 1854 this as well and formal documentation is simply lacking.

The 17-year and 13-year periodical cicadas only occur in the eastern half of the US (east of the Great Plains). They can be found from northeastern Texas all the way to New England.  They are especially abundant from Illinois east to the mid-Atlantic region.  In general, the 17-year periodical cicada broods have a northern distribution while the 13-year broods have a more southern distribution.

The US Forest Service has an excellent color-coded map to help understand where these insects occur.

For how abundant the periodical cicadas can be when they emerge, the geographical record of these in Wisconsin is poorly documented and many old records are simply at the county-level.  Although historical maps make it seem like these cicadas can be found throughout southern Wisconsin, they’re really restricted to individual spots on the map.

Some of the key sites with historical reports include Beloit, Janesville, Prairie du Chien, and Spring Green. Additional sightings have been reported in locations such as Arena, Burlington, Delevan, Dodgeville, Evansville, Kansasville, and Mazomanie. Perhaps the single best known location for these in Wisconsin is the Lake Geneva area. Larger cities such as Milwaukee and Madison do not have known periodical cicada activity (no reports from either 1990 or 2007). Overall, there will be much more periodical cicada activity in Illinois compared to Wisconsin.

See the When & Where page for additional details, including maps.

One of the best questions related to this is, “have you lived in the same area in 2007?”. If you lived in the same area 17 years ago and did not see periodical cicadas, then it’s highly unlikely that you’ll see them this year. Periodical cicadas emerge in the same spots over time and their dispersal from those areas in minimal.

See the above question and the When & Where page for additional details. In general, most Wisconsinites will not have these in their yards or neighborhoods this year, meaning that if you want to experience them for yourself, you’ll likely need to travel to do so.

Habitat destruction (e.g., land-use changes, development, urbanization, etc.) is perhaps the biggest immediate threat to periodical cicadas. Periodical cicadas emerge in the same spots over time and their dispersal from those areas in minimal.  Since these insects feed on trees, they have historically been associated with wooded areas and orchards. If historical cicada habitat has been razed for agricultural, residential, or commercial use, those cicadas populations will perish.

The periodical cicadas emerge earlier in the year than our typical dog-day cicadas. A big factor for periodical cicada emergence is the temperature of the soil. Scientists have found that periodical cicadas emerge when soil temperatures at a depth of 8 inches exceeds 64˚F (18˚C). Based on records from the Brood XIII activity in 1990 and 2007, these cicadas have typically become active in mid-to-late May in parts of Illinois. In Wisconsin, emergence often begins in late May with most activity occurring in the month of June.

Keep in mind that El Niño, climate change, and spring weather patterns could potentially shift things earlier this year.  Some websites provide interactive soil temperature maps, such as this one from the Wisconsin Environmental Mesonet  (Wisconet) network of weather monitoring stations (select 8″ soil depth from the pull down menu at the top of the map).

Yes. Occasionally, relatively small numbers of periodical cicadas can emerge out of sync compared to the main group (usually 4 years ± from the expected emergence).  These are referred to as “stragglers” and some Brood XIII stragglers were reported in 2020 in Wisconsin and Illinois.

If you’re in a cicada hotspot at the right time, the emergence will truly be an amazing sight to behold. The cicada nymphs (juveniles) burrow upwards from below ground and leave holes in the ground where they emerge. Sometimes as many as 25 emergence holes can occur per square foot. After emerging the nymphs climb onto nearby objects, such as tree trunks, to molt and transform to the adult stage. After shedding their exoskeleton, the pale-colored, newly-emerged adults have to allow their wings to expand. Within a short period of time, their body color darkens from pale to blackish.

In some cases, periodical cicadas can be found in densities of hundreds of thousands or even millions per acre. The sheer number of cicadas can create a surreal atmosphere, as they cover trees, sidewalks, and other surfaces. Shortly after the adults appear, they’ll be looking to mate, and the insect concert begins.  For the period of adult activity (roughly a month), it’ll be a noisy situation that could interfere with nearby outdoor activities. After this time, the adult cicadas will die, leaving large numbers of dead cicadas in the nearby area. That may require some sweeping or shoveling from driveways, patios, and sidewalks, but think of this as free fertilizer for your yard!

This video will give you a good idea of what the experience can be like:

Only male periodical cicadas “sing”.  To produce sound, males possess drum-like membranes (tymbals) on the sides of their abdomens. Rapid muscle contractions cause the shape of the tymbals to change which produces sound. Male abdomens are mostly hollow, and the resulting air space further plays a role in sound production.

Cicada singing is for mating purposes—males sing or call to attract females.  The exact frequency and pattern of the singing can vary for each type of cicada. At close range, female periodical cicadas can flick their wings to produce a brief snapping noise, which can lead to a back-and-forth between males and females before mating.

The famous naturalist, Sir David Attenborough, even mimics this on film with amusing results!

For their small size, individual cicadas are surprisingly loud. A group of periodical cicadas in nearby trees can produce sound in the ballpark of 80 decibels (louder than a vacuum cleaner).  Sound levels very close to calling cicadas could be close to 100 db (similar to a motorcycle or snowmobile).

The Brood XIII periodical cicadas that we have in Wisconsin have 17-year life cycles. When adults are active, they mate and lay eggs in twigs and small branches of trees. After a while, the eggs hatch and the young cicada nymphs (juveniles) drop to the ground where they’ll spend the vast majority of their lives. The cicada nymphs burrow down into the soil (typically do a depth of 8-12 inches) and use their sucking mouthparts to drink sap from tree roots. Despite feeding on tree roots, they cause a trivial amount of damage to the plants. The cicada nymphs continue to develop below ground and emerge 17 years later to transform to the adult stage and reproduce. Adults are short-lived (roughly a month) and don’t generally feed—they’re mostly focused on finding a mate!

The sheer numbers may assist with survival.

Many vertebrates (birds, mammals, etc.) will gorge themselves on the abundant cicadas as they emerge. By emerging in such large numbers, some cicadas should be able to reproduce, even when many others are eaten.

Yes—and they’re a good protein source.  Many vertebrates (birds, mammals, etc.) will gorge themselves on the abundant cicadas when they emerge.

Worldwide, humans consume cicadas and other insects as a regular part of their diet. Historical notes documenting periodical cicada activity in North America over the last 400+ years have often mentioned human consumption of the readily-available cicadas. In more recent times, some have even embraced entomophagy with the creation of cicada-centric recipe books.

If the idea of eating insects makes you squeamish, just keep in mind that foods such as shrimp, crabs, and lobster often have a hefty price tag at restaurants—yet those creatures are very closely related to cicadas and other insects!

Keep in mind that insects are related to shellfish, such as shrimp and crabs, so those with shellfish allergies should avoid trying cicadas out of an abundance of caution.

In short, no. These insects don’t sting or bite, although they can be noisy. If you happen to live in a cicada hotspot, cicadas could interfere with outdoor concerts, weddings, graduation parties, cookouts, and other gatherings, so you may need to postpone outdoor events until after cicada activity subsides or relocate to another area.

Cicadas are technically edible (see the question above) and wild animals have quite a feast when the cicadas emerge.  For pets, eating a few generally shouldn’t be a cause for concern, but eating large numbers is not recommended.  See this NPR story for more details.

Technically yes, although the type and size of plant has a big influence on the severity of damage.

Cicadas can cause damage to woody plants such as trees and shrubs. After mating, adult females use a spear-like structure known as an ovipositor to slice into twigs and small branches so that eggs can be deposited. This can cause the leaves on injured branches to turn brown and wilt.  In addition, affected twigs may break off. For large trees, this damage tends to be minimal as a small percentage of the overall canopy is affected. When this occurs on trees, the damage is referred to as “flagging”. Healthy trees usually withstand this temporary stress without long-term harm.

Damage could be more significant on small, newly planted trees as a much greater percentage of the canopy could be affected.

Periodical cicadas are known to be associated with over 70 different types of plants, including many of our common forest, landscape, and fruit trees.  Of all the recorded host plants, oaks are one of their favorites, but cicadas will lay eggs on a wide range of common plants including oak, maple, hickory, walnut, elm, birch, ash, dogwood, apple, peach, cherry, grape, and many others.

Research has found subtle differences in host plant preference between the species of periodical cicadas, but plant setting in the landscape may be a more important factor.  Scientists have determined that adult females looking to lay eggs prefer trees that receive a lot of sunlight over those that receive less.  For example, landscape or fruit trees growing out in the open and surrounded by low grassy plants would be a more suitable habitat than trees in the midst of the forest. Interestingly, periodical cicadas have long been documented in orchard settings, which offer plenty of sunlight.  Host plants must also have twigs/branches of the correct diameter (roughly 1/4 – 1/2 inch) for egg laying.

Generally, no.  Periodical cicadas are typically associated with trees, so crops such as corn, soybeans, alfalfa, vegetables, etc. should be unaffected.

Technically, cicadas can cause hard to certain (woody) agricultural crops, such as fruit trees and grape vines in orchard or vineyard settings.  Ornamental trees/shrubs grown in a nursery setting can also be affected.

In most cases, no.  A big factor is if you live in an area of expected cicada emergence.  If you don’t, then there’s no concern.  Plant size is another factor.  If you’re expecting cicadas in your area, large trees tend to tolerate damage from these insects without any ill effects. See the management box on the Good or Bad? page for additional details and a decision flowchart.

An easy way to protect ornamental trees/shrubs and fruit trees is to cover the plants with fine mesh netting (mesh size of 1/4″ or less).  The mesh netting can then be secured (tied, etc.) along the main trunk.  The netting will serve as a physical barrier to prevent cicadas from getting to the plant and this non-chemical approach has been shown to be really effective.  Pesticides are not recommended for cicadas and generally do a poor job of protecting plants.

If you live in a spot with expected cicada activity, one of the easiest options is to simply postpone planting any new trees or shrubs until after cicada activity subsides (July).  Waiting to plant will be an easy way to avoid damage entirely!