Cicadas are fascinating insects known for their loud songs and periodic emergences. Their life cycle involves a prolonged underground nymph stage, feeding on tree roots, before emerging as winged adults. Once above ground, their brief adult lives focus on reproduction. They are drawn to specific environmental cues crucial for their survival.
The Power of Sound
Sound plays the most significant role in attracting cicadas, particularly for mating. Male cicadas produce loud, species-specific calls to attract females. These sounds come from specialized organs called tymbals, ridged membranes on their abdomen. Powerful muscles rapidly vibrate these tymbals, creating sound waves. The male’s hollow abdomen acts as a resonating chamber, amplifying sounds to be incredibly loud.
These calls can reach 100 to 120 decibels, comparable to a motorcycle, making them among the loudest insect sounds. Females respond to male calls with a subtle wing flick, signaling receptiveness. The song’s timing and rhythm allow females to identify mates of their own species, even in a large chorus. Beyond mating calls, cicadas are also attracted by general vibrations or human-made noises like lawnmowers, potentially mistaking them for large chorusing centers.
The Pull of Light
Light, especially artificial light at night, also attracts cicadas, though not primarily for mating. This phenomenon, known as phototaxis, draws cicadas towards light sources. During mass emergences, many cicadas congregate around streetlights, porch lights, or other artificial illumination. This can lead to disorientation, as artificial light may confuse them, diverting them from natural flight paths or preventing them from finding suitable mating and egg-laying locations.
Their general draw to bright, sustained light sources is evident. This attraction can inadvertently draw them into urban areas or towards homes, especially during emergence when they seek to climb vertical surfaces. Artificial light can disrupt their natural nocturnal movements, typically guided by ambient light and environmental cues. This can result in large numbers gathering in unintended places, making them more visible and vulnerable.
Attraction to Host Plants
Cicadas are strongly attracted to specific trees and shrubs, essential host plants throughout their life cycle. Nymphs spend years underground, feeding on nutrient-rich xylem fluid from plant roots. Upon emergence, adults continue to feed on plant sap, primarily from young twigs and branches. They possess specialized piercing-sucking mouthparts to extract this fluid.
Female cicadas are particularly drawn to certain trees for egg-laying, using an ovipositor to create V-shaped slits in small branches. Each slit can hold multiple eggs, and a single female may lay hundreds. Deciduous trees are generally preferred, including oaks, maples, hickories, ash, and various fruit trees. These trees offer suitable sap for feeding and appropriate branch sizes for egg deposition. Coniferous trees are typically avoided for egg-laying due to their needles and sap.