Cicadas do not drink water like humans or other animals. Instead, they have a unique method for obtaining hydration directly from plants. This strategy is central to their entire life cycle, both as underground nymphs and above-ground adults.
How Cicadas Obtain Water
Cicadas acquire water by feeding on xylem sap, a fluid found within plants. They possess specialized piercing-sucking mouthparts, known as a proboscis, which functions like a straw. This structure allows them to pierce plant stems or roots and access the xylem tissue. The proboscis contains stylets, needle-like components that tap into the plant’s vascular system.
Adult cicadas feed on xylem sap from branches and twigs. Nymphs access xylem sap from plant roots. To extract this fluid, cicadas use powerful pumping muscles in their heads, creating the suction to draw sap into their bodies.
Xylem Sap as a Water Source
Xylem sap serves as the main source of both water and nutrients for cicadas. This fluid is predominantly water, making up about 99% of its composition. It also contains trace amounts of amino acids and minerals, with very low concentrations of carbohydrates. Due to its dilute nature and low nutritional content, cicadas must consume large volumes of xylem sap to obtain sufficient nutrients for growth and survival.
The negative pressure within the xylem of plants means cicadas must exert strong suction to draw the sap. Their reliance on this nutrient-poor fluid necessitates a high intake, making it both their food and drink. Specialized bacteria in the cicada’s gut help them process the nutrients found in xylem sap.
Processing and Excreting Excess Water
Given the large volumes of dilute xylem sap they consume, cicadas must process and excrete excess water efficiently. They can ingest up to 300 times their body weight in fluid daily. Much of this water is expelled as “honeydew,” a sugary waste product. This occurs as their digestive system filters out nutrients, leaving a sugar-rich liquid.
Unlike many smaller insects that excrete waste in droplets, cicadas release honeydew in high-speed jets, sometimes called “cicada rain.” This jetting behavior efficiently manages their vast fluid intake; flicking individual droplets would be too energy-intensive. This excretion method highlights their adaptation to a high-volume, low-nutrient diet.