Description

The resh cicada is one of several members of the large, loud “dog day cicada” group in Louisiana. Viewed dorsally, adults are primarily light green with black markings, and dark tan or gray abdomens. Color varies depending on the geographic location. Resh cicadas can be identified by unique markings on the second segment of the thorax (mesonotum; the area between the wing bases). The light green markings resemble a pair of inverted Hebrew letters spelling “resh”, from which its common name originates. A pair of orange markings are present on the sides of the thorax near the bases of the wings. Wings are broad and membranous with clouded first and second crossveins and light orange membranes along the trailing edges. Adult cicadas can be sexed by looking at the ventral side of their abdomens. Males have sound producing organs (tymbals) near the bases of their wings, and females possess a long, pointed egg laying apparatus (ovipositor) at the rear of their abdomens.

Eggs are shaped like a rice grain and about 5 mm in length. Newly hatched nymphs are elongate and pale but harden and darken shortly after burrowing into the soil. The subterranean immature stages are short, robust, wingless versions of the adults, tan or brown in color, with oversized forelegs used for digging. During late spring and early summer, nymphs can be seen on the surface climbing vertical surfaces prior to transforming into adults. Emergence holes on the surface of the ground are about 25 mm in diameter and are often mistaken for burrows of other organisms (e.g., snake holes). Freshly emerged (teneral) adults are pale, soft and require several hours to harden into sexually mature adults. Cast exoskeletons are hollow, rigid and remain firmly attached to vertical surfaces.

At least two other species of Megatibicen occur in Louisiana. Differences include size, detail of the wing veins, shape of the pronotal markings and degree of powdery coatings (pruinosity) on the body. Mating songs of the resh cicada are long, medium pitch, raspy trills lasting up to 10 seconds. Males of the species possess one of the loudest songs among U.S. cicadas and choruses usually comprise many males.

Life Cycle

Cicadas undergo three life stages, egg, nymph and adult (hemimetabolous life cycle). Resh cicadas are annual cicadas, meaning adults appear every year. Female cicadas lay eggs in slits of twigs or bark of trees using their saw-like ovipositors. Various species of oaks are favored. Nymphs hatch six to eight weeks later, drop to the ground, and immediately begin burrowing. They use their forelegs to dig tunnels into the root system of trees They feed on the root’s xylem using their piercing, sucking mouthparts. Nymphs remain underground for the duration of their developmental periods and undergo several growth stages (instars). Several years may be required for nymphal development. Generations overlap and are not synchronized as those of periodical cicadas. Adults typically emerge from the soil at night and require several hours to fully harden into flight capable individuals. Emergences occur annually from mid to late summer. Adult males begin chorusing immediately. Females find suitable singing males, mate and lay eggs, beginning the next generation.

Ecological Significance

Resh cicadas are distributed throughout the southern and central United States from Texas to Mississippi reaching north to Nebraska and Missouri. Egg laying on live twigs can cause minor damage known as flagging, in which branch tips die beyond the egg slits. Flagging does not damage trees but can be unsightly and mistaken for diseases or damage caused by other insect pests. Likewise, nymphal feeding does not damage trees except on rare occasions when population densities are unusually high.

Both adults and the subterranean nymphs are important food sources for insectivorous birds, reptiles and mammals. Small rodents and armadillos enthusiastically pursue the subterranean nymphs and birds and reptiles feast on the adults. Copperhead snakes (Agkistrodon spp.), not normally known as agile climbers, will climb trees in search of newly emerged nymphs and freshly molted adults during periods of cicada abundance. The song of individual male resh cicadas has been measured at 105.9 dB, possibly making it the loudest insect in the U.S. Some people find it annoying, but it is part of the natural soundscape in Louisiana.