Cicadas typically emerge during the late spring or early summer, once the soil temperature reaches about 64°F (18°C). The timing can vary depending on the species, with some appearing annually and others, known as periodical cicadas, emerging en masse every 13 or 17 years. Discover the intriguing cycle of cicadas and what triggers their synchronized emergence.
POINTS
- Cicadas typically emerge when the ground temperature reaches approximately 64 degrees Fahrenheit, usually during the spring or early summer months, with variations depending on geographic location and species, such as annual and periodical cicadas.
- Periodical cicadas emerge in large numbers after 13 or 17 years underground, with their emergences predicted by monitoring soil temperatures and historical patterns, such as the 2024 emergence of Brood XIX and Brood XIII.
- Cicada season lasts about 4 to 6 weeks, starting with the emergence of the first adults and ending with the death of the last adults after mating and egg-laying, with the peak marked by the highest number of singing males and visible adults.
- Adult cicadas have a short lifespan above ground and are typically gone by late summer or early fall, with the decrease in sightings and the quieting of their songs signaling the end of the season.
- Cicadas and locusts are distinctly different; cicadas are part of the Hemiptera order with predictable cycles, while locusts belong to the Orthoptera order and have irregular swarming events often linked to environmental conditions like drought and rapid vegetation growth.
Emergence Patterns of Cicadas
Cicadas are fascinating insects known for their loud, distinctive songs and their unique life cycles. Understanding when cicadas emerge can help us appreciate these creatures and prepare for their arrival.
Typical Time of Year and Conditions for Cicada Emergence
Cicadas typically emerge when the ground temperature reaches approximately 64 degrees Fahrenheit. This condition is usually met during the spring or early summer months. However, the exact timing of their emergence can vary based on geographic location and species.
Geographic Variations
In the southern regions of the United States, you might notice cicadas emerging earlier, sometimes as soon as late April or early May. In contrast, northern areas may not see cicadas until late May or June due to cooler soil temperatures.
Species Variations: Annual vs. Periodical
There are two main types of cicadas: annual cicadas and periodical cicadas. Annual cicadas, as their name suggests, emerge every year. Periodical cicadas, on the other hand, are known for their synchronized emergences in large numbers after 13 or 17 years underground, depending on the species.
How Often Do Cicadas Come Out?
The life cycles of cicadas are nothing short of extraordinary, with significant differences between annual and periodical species.
Annual Cicadas
Annual cicadas have a life cycle that spans 2 to 5 years, although they are seen every year due to overlapping generations. These cicadas spend most of their lives as nymphs underground before emerging to molt, mate, and lay eggs.
Periodical Cicadas
Periodical cicadas have either a 13-year or a 17-year life cycle, depending on the species. They spend the majority of their lives as nymphs underground, feeding on sap from tree roots. The entire brood emerges simultaneously after their long developmental period, creating a remarkable natural event.
Forecasting Emergences
Predicting cicada emergences involves monitoring soil temperatures and historical emergence patterns. There are several broods of periodical cicadas, each with its own emergence schedule. For instance, Brood X, the largest group of 17-year cicadas, last emerged in 2021. We can expect to see them again in 2038. In 2024, two broods will be active:
- Brood XIX (13-year cicadas): These cicadas will emerge in mid-May to late June in parts of the eastern United States, including Maryland, Virginia, and Washington, D.C. This is a rare event, as these two broods only overlap every 221 years.
- Brood XIII (17-year cicadas): These cicadas will emerge in parts of the Midwest and South, including Illinois, Indiana, Kentucky, Missouri, Ohio, Tennessee, and West Virginia. The exact timing will vary depending on the location, but they will generally emerge in late May to early June.
When is Cicada Season?
Cicada season refers to the period when adult cicadas are actively present above ground, engaging in their mating rituals.
Duration of Cicada Season
The start of cicada season is signaled by the emergence of the first adults and typically lasts for about 4 to 6 weeks. The season’s end is marked by the last of the adults dying off after successful mating and egg-laying.
Peak and Decline
The peak of cicada season is when the largest number of cicadas are visible, and their chorus is at its loudest. This peak occurs a few weeks after the initial emergence. As the season progresses, the number of singing males and visible adults declines, indicating the end of the active season.
When Do Cicadas Go Away?
Adult cicadas have a short lifespan above ground, usually not exceeding a few weeks. They are typically gone by late summer or early fall.
End of the Adult Cicadas’ Life
After mating, female cicadas lay their eggs in tree branches, and soon after, both male and female cicadas die. The decrease in sightings and the quieting of their songs signal that the cicadas are going away.
Post-Peak Activity
Following the peak, you may still observe some adults and hear intermittent singing, but these signs will diminish as the season closes. The end of the season is also evident when you start to find remnants of cicada activity, such as their shed exoskeletons or damaged foliage from egg-laying.
Misconceptions and Inaccuracies
A common misconception is that cicadas and locusts are the same because of their mass emergences. However, locust swarms are associated with crop damage and are considered pests, while cicadas do not form swarms and typically cause minimal harm to vegetation.
Timing and Frequency of Emergences
Locusts do not have a predictable cycle like cicadas. Instead, their outbreaks are irregular and often linked to periods of drought followed by rapid vegetation growth. This can lead to unpredictable swarming events that are not tied to a specific season or frequency.
Cicada Life Cycle Stages
The life cycle of a cicada is complex and consists of several stages from egg to adult.
Stages from Eggs, Nymphs to Adult Cicadas
Cicadas begin their life as eggs, which are laid in the twigs of trees. Once hatched, the nymphs fall to the ground and burrow underground, where they will spend the majority of their lives. After several years, they emerge from the soil, molt into adults, mate, and the cycle begins anew.
Larval and Hatching Stages
The larval stage of a cicada’s life cycle occurs entirely underground. As nymphs, they undergo several instars, molting and growing larger with each stage. When the nymphs are ready to emerge, they dig tunnels to the surface and climb onto a nearby plant or structure to molt for the final time and become winged adults.
Connection to Emergence
Understanding the larval and hatching stages is key to predicting when cicadas will emerge. By studying the development of nymphs and monitoring environmental cues like soil temperature, we can estimate the timing of their appearance above ground.
Why Do Cicadas Stay Underground for 17 Years?
The 17-year periodical cicadas, like Magicicada species, stay underground for 17 years as part of their evolutionary life cycle strategy to avoid predation. By emerging en masse after such a long period, they overwhelm predators with their sheer numbers, ensuring enough survivors to continue the species. This prime number emergence interval also helps avoid synchronizing with the life cycles of potential predators, further diminishing the chances of being eaten before they can reproduce.
