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Fig. 180.—End of abdomen of Æschna heros, ♀: ur, urosternite; or, outer, ir, inner styles of the ovipositor; 11, 11th abdominal segment; c, cercopod.

Fig. 181.—Larva of Sisyra, from beneath. B, an abdominal appendage.—After Westwood, from Sharp.

Fig. 182.—Cercopoda (P) of Mantis.—After Lacaze-Duthiers.

The anal cerci are present in the Orthoptera and, when multiarticulate, function as abdominal antennæ. They are longest in the Mantidæ (Fig. 182); they also occur in the larva of the saw-fly, Lyda (Fig. 183). Dr. A. Dohrn has stated that the cerci of Gryllotalpa are true sensory organs, and we have called those of the cockroach abdominal antennæ, having detected about ninety sacs on the upper side of each joint of the stylets, which are supposed to be olfactory in nature, and which are larger and more numerous than similar sacs or pits in the antennæ of the same insect.^[36] From his experiments upon decapitated cockroaches, Graber concluded that these cerci were organs of smell.

Fig. 183.—Lyda larva: a, head; b, end of body seen from above; c, from side, with cercopod.