Cicadas are one of nature’s most intriguing insects, known for their synchronized, periodic emergences that transform landscapes with their unique presence. These events, occurring on cycles of 13 or 17 years for some species, bring billions of these insects above ground for a brief but impactful phase of their lives. Understanding their activities during this time, especially what they consume, often sparks widespread curiosity.
The Exclusive Diet of Adult Cicadas
Adult cicadas primarily sustain themselves by drawing xylem sap from the twigs and branches of trees and woody shrubs. This liquid diet differs significantly from many other insects, as cicadas do not consume leaves, fruits, or other solid plant parts. They also do not prey on other insects. Xylem sap, the watery fluid transported through a plant’s vascular system, contains water, amino acids, and some minerals, but it is notably low in nutritional content.
Because the sap offers limited nourishment, adult cicadas must consume large quantities to meet their energy needs. Their short adult lifespan, typically only a few weeks, is largely dedicated to reproduction. Consequently, they rely heavily on the energy reserves accumulated during their much longer nymphal stage, which they spend underground.
How Cicadas Feed on Trees
Cicadas possess specialized mouthparts designed for piercing and sucking, enabling them to access the tree’s internal fluids. This feeding apparatus is commonly referred to as a proboscis, rostrum, or beak. The cicada uses this needle-like structure to penetrate the outer bark and reach the xylem tissue within the tree’s branches.
Cicadas slowly work their beak into the branch, sometimes rocking back and forth to facilitate entry. Unlike insects with chewing mouthparts, cicadas do not bite off or chew plant material. They can remain attached and feed for several hours at a time.
Minimal Impact on Trees and Common Misconceptions
Adult cicada feeding generally has minimal impact on mature, healthy trees. The most visible sign of their presence is “flagging,” browned, withered branch tips. Flagging is not from feeding, but occurs when female cicadas cut small slits into pencil-sized branches to deposit eggs, weakening the branch tips. While dramatic, flagging is primarily a cosmetic issue for established trees.
A frequent misconception is that cicadas devour garden plants, flowers, or agricultural crops; however, they do not eat these types of plants. Their specialized mouthparts are only suited for extracting sap from woody plants. This behavior contrasts sharply with locusts, which possess chewing mouthparts and can cause widespread destruction to crops and other vegetation. Young trees, especially those recently planted or with slender branches, are more vulnerable to damage from egg-laying, which can sometimes impede their growth or cause significant stress.