Neotibicen pronotalis also colloquially called Walker's cicada is a large annual cicada, one of the largest species of North American Neotibicen. The name of this species has undergone numerous changes. One of its two subspecies was originally known as Tibicen marginalis, and later renamed T. walkeri. The other subspecies was described as Tibicen pronotalis but this is an older name than walkeri, and therefore takes priority. The genus name was changed in July 2015 due to taxonomic reconfiguration of the genus Tibicen. This insect is of no economic importance.
Description and identification
This cicada is the loudest calling Eastern Neotibicen species, with male alarm calls recorded at 105.9 dB. Neotibicen pronotalis is a large cicada with males reaching up to 40 millimetres (1.6 in) (body length not including wings), but it averages from 36–39 millimetres (1.4–1.5 in); rivaling Neotibicen auletes and Neotibicen resonans in size (N. auletes and N. resonans are other species of large North American cicadas). Adult N. pronotalis vary considerably in appearance. Pronotum coloration may be sandy orange, tan, lime green, ocherous yellow, dull yellow or orange, or any combination of these. Eye coloration varies as well, most individuals though, have slate blue eyes, although some may have green, brown, or tan eyes . The venter is lightly pruinosed. N. pronotalis have variable mesonotal coloration and patterning, which can be the typical well-defined Neotibicen mesonotal patterns or dark, obscure patterns. Mesontal colors are usually tan, red, and black. The abdomen is a dark gray or black. N. pronotalis can be found throughout much of the Midwestern and Southeastern United States Neotibicen pronotalis has two subspecies, both equally common, Neotibicen pronotalis walkeri and Neotibicen pronotalis pronotalis, pronotalis individuals generally have a black pronotal blotch, while walkeri individuals lack a pronotal blotch. The call of N. pronotalis is identical to that of a similar species, Neotibicen dealbatus. For this reason, the two can be commonly confused.
This species is widespread west of the Appalachian Mountains. It has been reported from Alabama, Arkansas, Florida, Georgia, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Michigan, Missouri, Minnesota, Mississippi, Nebraska, North Dakota, Ohio, Oklahoma, South Dakota, Tennessee, Texas, Virginia, West Virginia, Wisconsin, and Wyoming in the United States. Populations north and west of the Mississippi river are representative of N. pronotalis pronotalis, while those east and south of the Mississippi are representative of N. pronotalis walkeri.
N. pronotalis is common on the hottest of summer evenings and afternoons ("dog days"). It is active from as early as 7 a.m. to as late as 10 p.m., with peak activity from 12 p.m. to 4 p.m. In most of their range N. pronotalis can be heard from July to October, with peak activity in August.
This is generally, but not exclusively, a riparian species; favoring small trees and low vegetation along rivers, creeks, and floodplains. Although not host specific, Neotibicen pronotalis is often associated with cottonwoods (Populus) and willows (Salix), as well as sycamores (Platanus) rather than other floodplain hardwoods. They are also found in urbanized and residential areas, parks, woodlots, and overgrown fields and pastures. For insect collectors, these cicadas prove difficult to catch because the habitat they are found in can be difficult to navigate. They are rarely seen and mostly heard, were males call to females from the tops of trees. Cicadas are also attracted to UV lights during the night, and exhausted cicadas be seen resting below lights at night.
This cicada feeds on sap that comes from all trees, though they prefer cottonwood and willow. As nymphs they feed on the sap that comes from the roots of trees.
Males call to females from trees where they are well hidden. The call is a loud, extended dry rattling trill or drone, produced by a powerful muscle on the male's underside called a tymbal, it contracts and relaxes a membrane and as the membrane moves it clicks, the clicks are amplified because the inside of the insect is mostly hollow. Males of this species commonly form large singing aggregations in trees as they try to woo a female. Healthy males have a loud and steady call. Females click their wings together as an indication to a mate. After mating, the female lays her eggs, preferably in a dead tree branch. The cicada slits an opening in the branch and inserts the eggs using an ovipositor. Later, the eggs hatch and the nymphs fall to the ground and burrow there for three to five years. During their subterranean life, nymphs feed on sap from the roots of trees; and pass through multiple instars before finally emerging when the soil temperature warms in the summer. When the nymphs emerge; typically at night, they ascend a tree trunk or other sturdy structure and undergo ecdysis. The molted exoskeletons; also known as exuviae, are left behind. These shrivel and turn brown and can commonly be found attached to tree trunks and other objects. Aboveground, the duration of a cicada's life typically does not exceed 2 months.
Cicadas have many predators because they have few defenses. Common predators include squirrels, raccoons, opossums, and birds such as: blue jays, common grackles, house sparrows, American crows, and sometimes northern cardinals. House sparrows chase cicadas in mid-air often hawking them in air and trying to catch them. Blue jays catch cicadas and pin them down with their feet, and then crush and eat them discarding the wings. Cicadas are rarely consumed by spiders due to their rather bulky size and hard exoskeleton. Cicada killer wasps are also a threat to cicadas. Female wasps hunt cicadas by sight. After locating a cicada they sting it, paralyzing it. They then drag the paralyzed cicada up tree trunk or fence and fly away with it. They bury the cicada in their nest which is a 3-inch hole underground. The female lays her eggs and closes the hole. The eggs hatch and the larvae begin feeding on the cicadas. They emerge the following spring. Cicadas commonly spray water at their predator, or fly away. Males when captured will emit a loud alarm call.
- "Description of a new genus, Auritibicen gen. nov., of Cryptotympanini Hemiptera: Cicadidae) with redescriptions of Auritibicen pekinensis (Haupt, 1924) comb. nov. and Auritibicen slocumi (Chen, 1943) comb. nov. from China and a key to the species of Auritibicen | LEE | Zootaxa". biotaxa.org. Retrieved 2015-07-11.
- KATHY B. R. HILL; DAVID C. MARSHALL; MAXWELL S. MOULDS; CHRIS SIMON (25 December 1999). "Molecular phylogenetics, diversification, and systematics of Tibicen Latreille 1825 and allied cicadas of the tribe Cryptotympanini, with three new genera and emphasis on species from the USA and Canada" (PDF). Zootaxa. 3985 (2): 219–251. ISSN 1175-5326. Retrieved 2015-07-12.