Cicadas

Cicadidae. Spanish: Chicharras (General);

coyuyos, cigarras (Argentina).

Portuguese: Cigarras.

Among homopterans, cicadas are famous for their sound-producing abilities. (A few others have vocal organs but none so well developed or capable as those of Cicadidae, and nothing is known of their function in Neotropical forms.)

On the back of the first abdominal segment there is a pair of exposed (or protected by a fold of the body wall), taut membranes (tymbals) that may be made to rapidly vibrate by well-developed oblique muscles. The tymbals vibrate extremely fast, producing a loud, sometimes strident, steady or pulsating buzz or siren scream that varies in pitch, pulse, intensity, duration, or other acoustic quality according to species. One type (tentatively determined as the very widespread Quesada gigas; fig. 8.6a) in park trees in Caracas emits a fairly deafening, throbbing wail. Some species are silent or produce only interrupted clicks.

Both sexes have auditory tympani anteriorly on the underside of the abdomen, concealed beneath large protective plates (not to be confused with the tymbals). Males often congregate on trees in forests and join their voices in intense synchronized chorusing that acts as a call to assemble females for mating. This aggregative behavior seems to be exhibited in secondary habitats and on trees that are the nymphal hosts (Young 1980). The latter are varied hardwoods and palms (Young 1973). Peaks of singing intensity occur in many species at dawn and dusk (Young 19816).

On trees, females insert masses of eggs in twigs or fronds with an ovipositor adapted for slitting bark. In many species, oviposition is limited to dead trees and fronds in the forest understory, while others put their eggs into dead grasses near

Figure 8.6 WAX BUGS, (a) Giant cicada (Quesada gigas, Cicadidae). (b) Spotted cicada (Zam-mara smaragdina, Cicadidae). (c) Cicada nymph (Cicadidae). (d) Ground pearls (Margarodes for-micarum, Margarodidae), females, (e) Axin (Uaveia axin, Margarodidae).

the ground. The nymphs drop to the soil and burrow deeply. They commonly spend two (but some, several to many) years underground, feeding on sap from the host's roots. On maturity, they crawl out of the ground and up onto tree trunks and limbs to transform. Fixed to such surfaces, their cast skins, split widely down the back, are a common sight. The nymphs of at least one Amazonian cicada (Fidicina chloro-gena; Ginzberger 1934) constructs tall (20-30 cm), hollow, mud chimneys in which to pass their final days before becoming adults.

The imagos are presumed to be shortlived, perhaps existing from a few weeks to a few months. They imbibe fluids from the xylem tissue of their hosts with a sturdy, jointed proboscis. Most are active in the forest canopy, although some species frequent the trunks of trees close to the ground. Few additional details of tropical cicadan biology are available, and these are mostly from species in Costa Rica (Young 1981a). Others (Bartholomew and Barn-hart 1984) have studied flight metabolism in the Central American F. manifera. It can fly at a body temperature of 22° C., but takeoff must be preceded by warming up by body movements. During active flight, the body heats up to 33° C. They do not

J jump but are easily excited and frightened II into flight.

■ Adults are easily distinguished as a

■ group by their robust form large size (BL

■ °f most 20-50 mm), and membranous wings, the anterior pair of which are almost twice as long as the posterior and extending well beyond the end of the body when folded. A transversely ridged swelling on the face and the singing organs of the male also are unique features of the family. The lateral margins of the thorax have winglike flanges in some, for example, Zammara (fig. 8.6b). The bodies of most cicadas are marked with green or white against a black background. The wing veins are usually dark, the color usually staining only the adjoining membrane, although the usually transparent membranous areas may be splotched with brown patterns as well.

Nymphs (fig. 8.6c) are stout-bodied, brownish, molelike creatures with out-sized, powerful fore tibiae and otherwise heavy legs adapted for digging. The abdomen is stubby and curved downward.

Cicadas seldom cause economic damage to plants with their feeding and ovi-position. They have been recorded molesting fruit trees and coffee in Brazil (da Fonseca 1945).

A complete bibliography on the family to 1956 is available (Metcalf 1962). The species are cataloged by Metcalf (1963a, 19636, 1963c) and Duffels and van der Laan (1985). The number of described Latin American species is roughly estimated at over 800, in some 80 or so genera; the former figure may represent as few as 60 percent of those that are to be found (Moore pers. comm.).

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