The taste-cups of the leaf-beetles are fairly numerous, judging from an examination of Diabrotica vittata. The surface of the epipharynx is pilose, but the median region is naked, and on the anterior half bears from 11 to 12 taste-cups, arranged each side of the median line in a rude Y. On each side, at the base of the labial region, are two sensitive fields, each bearing about 25 to 26 taste-cups. More were seen under the clypeus.
In the Neuroptera unmistakable taste-cups are not always present. In Sialis infumata along the median line of the epipharynx and near the front are about 20 scattered gustatory pegs, which are minute, but longer and more acute than usual. In Chauliodes maculatus there are one or two taste-cups under the front edge of the clypeus; others are scattered along the middle from the base of the labrum to the front, but are not arranged in definite order. In Corydalis cornutus no sense-cups, pits, or rods are present. In Chrysopa there are scattered cups armed with a short acute bristle, which are possibly gustatory in function. In Myrmeleon diversum also the presence of sense-pits or of taste-cups is doubtful, though a group of about 12 pits on each side of the clypeal region of the epipharynx, and a few situated at the base of the labral region, may be endowed with the sense of taste. In Mantispa brunnea, however, along the middle of the epipharynx are scattered about 30 unmistakable taste-cups, each bearing a short, fine hair.
In the Mecoptera (Panorpa debilis?) taste-cups, giving rise to a minute hair, occur on the labium in two regions, and also on the maxillæ situated on the stipes near the base of the palpi, and on the lacinia and galea. They are also to be found on the maxillæ of Boreus californicus, but were not detected on the labium.
They were first detected by Reuter in various microlepidoptera, and occur on the “basal spot” of the palpi of many butterflies. In a Tineid moth (Coleophora coruscipennella) we have detected what we suppose to be a group of four taste-pits on the inner side of the basal joint of the labial palpi.
Experimental proof.—No one, says Lubbock, who has ever watched a bee or wasp can entertain the slightest doubt as to their possession of the sense of taste. “Forel mixed morphine and strychnine with some honey, which he offered to his ants. Their antennæ gave them no warning. The smell of the honey attracted them, and they began to feed; but the moment the honey touched their lips they perceived the fraud.”
Will at first fed wasps with sugar, so that they frequently visited it; afterwards he substituted alum for the sugar. Eagerly flying to it, they had scarcely touched it when they drew back from the distasteful substance with the most comical gestures, and cleaned their tongues by frequently running them in and out, repeatedly stroking them with their fore feet. He noticed a great repugnance to quinine in nearly all the insects experimented on. Bees and wasps were observed to have a more delicate gustatory sense than flies, etc., which are more omnivorous in their tastes.
LITERATURE ON THE ORGANS OF TASTE
Meinert, F. Bidrag til de danske myrers naturhistorie. (Kgl. Dansk Vidensk. selsk. skrifter. Kjoebenhavn. Raekke 5 Naturvid. og math. Afd., v, 1861, pp. 273–340.)
Wolff, O. J. B. Das Riechorgan der Biene. (Nova acta d. K. Leop.-Carol. Akad., xxxviii, 1875, pp. 1–251, 8 Taf.)
Joseph, G. Zur Morphologie des Geschmacksorganes bei Insekten. (Amtlicher Bericht der 50. Versammlung deutscher Naturforscher und Aerzte in München, 1877, pp. 227–228.)