Fig. 30. Views of the female cicada's abdomen, including the egg-laying ovipositor, marked "Ovp" in illustration A (92).
At its base the abdomen is broadly but movably joined to the thorax, but the connecting parts are mostly concealed by overlapping parts of the metathorax. When the thorax and the abdomen are somewhat pulled apart, as shown at B of the same figure, it is seen that there lies in the infolded membrane between the metatergum (T3) and the first abdominal tergum (IT) a well-developed narrow postnotal plate of the metathorax (PN3), which bears the large third phragma, and is fused ventrally with the metapleural epimera (Epm3) in the usual manner. . .The [first abdominal tergum] (IT) is a narrow, transverse plate united with the second tergum (IIT); its lateral part presents an enlarged oval area (b), which corresponds with the area of the sound-producing cymbal of the male. (91-92)Snodgrass continues by describing the sound mechanism in the cicada’s abdomen:
The sternal plates of the first and second abdominal segments are highly modified, and they are separated by a deep inflection that forms a large ventral cavity at the base of the abdomen. This cavity is ordinarily closed to a narrow slit between the sternal plates. . .In the male cicada the cavity is much larger than in the female and contains the so-called “resonance” membranes, or “mirrors”, which are now regarded as tympana for the reception of sound vibrations. . .The tympanal cavity can be opened and closed by movements of levation and depression of the abdomen on the lateral hinges (fig. 30 B, a) between the postnotum and the first abdominal tergum, the movements being produced by the dorsal and ventral muscles of the first abdominal segment. (92-93)
The female cicada’s egg-laying ovipositor is visible in fig. 30 as “Ovp.” Snodgrass says that “Above the seventh sternum [see fig. 30 A, VIIS] is a small vestibular cavity (fig. 32 A, Vst), in the anterior wall of which is a large genital opening (a) above a small fold (VIIIStn), which is the posterior lip of the otherwise invaginated eighth sternum. The genital aperture may be exposed by depressing the seventh sternum, or by pulling the latter forward (fig. 31 A, a). It leads into a large copulatory pouch (GC), which. . .is the true genital chamber” (95).
Male and Female Magicicada septendecim mating. From Fontaine K, Cooley J, Simon C (2007). "Evidence for Paternal Leakage in Hybrid Periodical Cicadas (Hemiptera: Magicicada spp.)
Written by: Laurel Byrnes, Marketing Intern for the Biodiversity Heritage Library