Species Megatibicen dealbatus - Plains Cicada

Suggested: "Plains Harvest-fly" or "Whitewashed Harvest-fly"

First described in 1915 by William T. Davis as Cicada marginata var. dealbata

dealbata is Latin for "whitewashed, whitened"

There are currently no recognized subspecies; however, there are slight tendencies in traits and some minor differences (i.e. size, color, patterns, etc.) between and among populations relative to geographic distribution and overlap in characteristics with the related taxon, Tibicen pronotalis (see related links below).

The sister taxon Tibicen pronotalis replaces dealbatus across the eastern "Great Plains", Mississippi River basin and Southeastern USA. T. pronotalis is currently recognized as a distinct species; however, these "populations" appear to be closely related and possess similar morphology, calls, calling behaviors and host associations.

"Northern-Western race"

Tibicen pronotalis pronotalis

Tibicen pronotalis pronotalis var. pronotalis

Tibicen pronotalis pronotalis var. walkeri

"Southern-Eastern race"

Tibicen pronotalis walkeri

"Possible Hybrids/Transitionals"

Tibicen pronotalis nr. dealbatus (?)

Tibicen dealbatus nr. pronotalis (?)

T. pronotalis vs. T. dealbatus from Comment on this image by Bill Reynolds

Distinquishing traits of T. dealbatus are as follows:

1) ABDOMEN: T. dealbatus exhibits greater pruinosity (white powdered wax) than seen in pronotalis. The pruinosity is usually arranged in "dotted stripes" along the sides of the abdomen and dorsal abdominal midline (rare in pronotalis).

2) THORAX: T. dealbatus exhibits greater pruinosity on the thorax (esp. the mesonotum)

Often similar in appearance and confused with "The dorsatus Group"

Tibicen dorsatus (Say 1825), "Grand Western Annual Cicada" or "Bush Cicada"

Tibicen tremulus (nov. sp.), a.k.a. "Bush Cicada"

3) T. dealbatus is usually a bit more compact and has a slightly narrower head than seen in pronotalis

4) COLORATION: Variable in both taxa and not entirely diagnostic!, - tendencies - when T. dealbatus is green, it is typically a duller "pea green" (often more of a ~lime green in pronotalis) - when tan, it is typically more of a sandy-brownish tan as opposed to a ochreous yellow or taupe (green-tan) seen in pronotalis.

5) DISTRIBUTION: Geographic distribution of pronotalis and dealbatus and how they may relate.

To date, neither pronotalis nor dealbatus seem to be sympatric in their "pure" form. Although there is evidence to suggest genetic exchange and blending among adjacent populations (pronotalis x dealbatus), it is unlikely to find both taxa in their "pure forms" coexisting side by side.

6) WINGS: The costal margins of the forewings - heavy veins of the leading wing edge - are usually bowed or noticeably arciform as in pronotalis (more so than seen in several similar species).

Like pronotalis, the heavily infuscated (i.e. smoky black-grey) "Z" visible towards the ends of the forewings, and typical of most Tibicen species, is usually poorly developed to absent with only the cross veins being evident (i.e. The radial and radiomedial cross veins of tegmina, forewing, NOT heavily infuscated or darkened.).

7) CALL: The call of dealbatus is identical to that of pronotalis and may be described as a deep rhythmic "Yeee-Yeee-Yeee-....." with a subtle underlying rumble ..."broom-broom-broom-...." (difficult to vocally immulate or "spell out"). This species calls from late afternoon 'til well after sunset. The calls of the males are often heard as late as 10 to 11 PM (CDT/MDT).

HYPOTHETICAL: Based on call, behaviors, host affinities and morphology, Tibicen dealbatus (Davis 1915), "Plains Cicada" (no accepted common name applies) and Tibicen pronotalis Davis 1938 - [syn. marginalis (Walker 1852)], "Walker's Cicada" are possibly conspecific representing a cline.

Replaces T. pronotalis in the Plains States

Reported from the following: Montana, South Dakota, Nebraska, Kansas, Oklahoma, Texas, Colorado & New Mexico

usu. associated with Riparian ecosystems plentiful in Cottonwoods & Willows (+ adj./associated Hardwood forests and grasslands)

For most parts of the range, July-Sept

June-Oct across the southern part of the range

This species (& related taxa - pronotalis & cultriformis) seems to prefer cottonwoods & willows (Salicaceae)

Also reported from sycamore (Platanaceae) & less commonly associated with maples and misc. other flood plain hardwoods.

eggs usually laid in dead twigs, wood or bark

(occasionally eggs may be laid in living stems and twigs)

eggs hatch and nymphs burrow into the soil

nymphs feed on the sap in roots for several years (prefer Pines)

Final instar nymphs emerge and develop into winged adults (emergence for this species usu. occurs at night)

Tibicen dealbatus largely replaces T. pronotalis as one travels west into the "Plains". Both T. dealbatus and T. pronotalis are riparian species often associated with tree thickets and permanent/quasi-permanent water sheds. Not only are they similar ecologically, they are very similar behaviorally and the calls of the males are identical.

They are also thought to intergrade along a thin band where the ranges abut. The males of both dealbatus and pronotalis will often call an hour or two after sunset, a strange behavior for Tibicen here in the US...as most other species call from sunrise to sunset and rarely later.

I have observed dealbatus specimens from southern Texas are often larger and browner than those from Kansas and Nebraska. It seems as though populations along the southern perimeter of the range are often browner and rarely characterized by the greens seen in many populations in the heart of the Plains (Kansas, Nebraska, South Dakota, & Montana). Regarding brown coloration in T. dealbatus, read comments by David J. Ferguson here

Based on pruinosity and pattern, this species is often confused with Tibicen dorsatus (Say 1825), "Grand Western Annual Cicada" or "Bush Cicada"

_________________________________________________________________________________________________________________

Based on behavior and call, this taxon is most closely related to T. pronotalis

HYPOTHETICAL: Based on call, behaviors, host affinities and morphology, Tibicen dealbatus (Davis 1915), "Plains Cicada" (no accepted common name applies) and Tibicen pronotalis Davis 1938 - [syn. marginalis (Walker 1852)], "Walker's Cicada" are possibly conspecific and represnt a cline.

_________________________________________________________________________________________________________________

Compare to the following:

"The pronotalis Group"

Tibicen pronotalis Davis 1938 - [syn. marginalis (Walker 1852)], "Walker's Cicada"

Tibicen pronotalis x dealbatus intergrades

Tibicen dealbatus (Davis 1915), "Plains Cicada" (no accepted common name applies)

Tibicen cultriformis (Davis 1915), "Grand Western Flood Plain Cicada"

"The auletes Group"

Tibicen auletes (Germar 1834), "Northern Dusk Singing Cicada"

Tibicen resh (Haldeman1852), "Resh Cicada"

Tibicen resonans (Walker 1850), "Southern Resonant/Pine Barrens Cicada"

Tibicen figuratus (Walker 1858), "Fall Southeastern Dusk-singing Cicada"

"The dorsatus Group"

Tibicen dorsatus (Say 1825), "Grand Western Annual Cicada" or "Bush Cicada"

Journal of the New York Entomological Society, v.23, p.162    Davis' original description of the species