Fig. 288.—Tongue of worker honey-bee: pg, paraglossæ; B, the same enlarged, showing the taste-papillæ; C, D, base of a labial palpus (mx.′p) with the taste-papillæ; E, taste-cups on paraglossæ of Bombus; F, group of same on left, G, on right side, at base of labial palpus.
In the Odonata, however, they are fairly well developed; in Calopteryx, about 50 taste-cups were discovered; in a species of Diplax about 28, there being a group of 14 at the base of the epipharynx on each side of the median line, while in Æschna heros there are two groups of from 25 to 30 taste-cups, situated as in the two aforenamed genera.
In the Orthoptera the gustatory cups are numerous, well developed, and present in all the families except the Phasmidæ, where, however, they may yet be found to occur.
In a large cockroach (Blabera) from Cuba they are well developed. On each side of the middle of the epipharynx is a curved row of stiff, defensive spines, and at the distal end of each row is a sensory field, containing 20 taste-cups on one side and 23 on the other. Near the front edge of the clypeal region are two more sensory fields, situated on each side of the median line, there being 35 taste-cups in each field. The taste-cups in this form are rather smaller than usual in the order.
In the Acrydiidæ they are more numerous than in the Blattidæ. For example, in Camnula pellucida, near what corresponds to the front edge of the clypeus are two gustatory fields, each bearing about 35 taste-pits. Just in front, under the clypeo-labral suture, are two similar fields, each containing from 40 to 42 taste-pits. There are none in front of these. There are thus about 140–150 sense-cups in all.
The members of the Locustidæ (Fig. 26) appear to be better provided with the organs of taste than any other Orthoptera, those of the katydid numbering from 170 to 180. There are from 50 to 60 taste-cups in the front region; behind the middle a group of 25 on each side, and over an area corresponding to the base of the labrum and front edge of the clypeus is a sensory field with about 70 taste-cups on each side. They are true cups or beaker-like papillæ, some with a fine, others with a short, stout, conical seta.
The gustatory organs in the cave cricket (Hadenœcus subterraneus, Fig. 27), from Mammoth Cave, are highly developed, being rounded papillæ with the nucleus at the top or end. They are grouped on each side of the middle near the front edge, there being 25 on each side. An irregular row of these beaker-like organs extends along each side; some occur under the base of the labrum, but they are most numerous in a field corresponding to the front edge of the clypeus, there being 50 on each side, or 100 in all, where in Ceuthophilus there are only 9 or 10. It would thus appear as if the sense of taste were much more acute in the cave-dweller than in the out-of-doors form.
In the Coleoptera taste-cups and setæ are very generally distributed, though we were unable to detect them in Dendroctonus or in Lucanus dama. As seen in Fig. 57, we have observed numerous taste-pegs along the maxilla of Nemognatha lurida, but otherwise taste-organs have only been detected in the epipharynx. They not only occur in the adult beetles, but we have found them in the larvæ of cerambycid, scarabæid, and other beetles. In the adults taste-cups appear to be about as well developed in the carnivorous forms (Carabidæ) as in the phytophagous or lignivorous groups.
In Chlænius tomentosus there are about half as many of these organs as in Harpalus, while in Calosoma there are 90 taste-cups, 45 on each side, under the base of the labrum. The cups are papilliform, being rather high, with a seta arising from each.
In the Cicindelidæ, the epipharynx bears a sensory field quite different from that of the Carabidæ. There are no normal taste-cups, except a few situated on two large, round, raised areas which are guarded in front by a few very long setæ. On the surface of each area are numerous very long setæ which may, if not tactile, have some other sense, as they arise from cup-like bases or cells. Those on the outside are like true taste-cups, with a bristle but little larger than normal in taste-cups generally. We are disposed to regard this sensory field as a highly specialized gustatory apparatus.