Such obvious features as the number of segments in the foot and the shape of the feeler were used by the early entomologists for distinguishing the great groups of beetles.
The Passalidae are a tropical family of beetles generally considered to be intermediate between stag-beetles and chafers, the enlarged segments of the feeler being capable of close approximation.
Fielde show that an ant follows her own old track by a scent exercised by the tenth segment of the feeler, recognizes other inmates of her nest by a sense of smell resident in the eleventh segment, is guided to the eggs, maggots and pupae, which she has to tend, by sensation through the eighth and ninth segments, and appreciates the general smell of the nest itself by means of organs in the twelfth segment.
- a, Saw-toothed Grain-Beetle (Silvanus surinamensis); b, pupa; c, larva, magnified 12 times; d, feeler of larva.
I and 25) have the terminal antennal segments pectinate, and so arranged that the comb-like part of the feeler cannot be curled up, while the elytra completely cover the abdomen.
An ear of another type is found in the swollen second segment of the feeler in many male gnats and midges, the cuticle between this segment and the third forming an annular drum which is connected with numerous nerveendings, while the fine bristles on the more distal segments vibrate in response to the note produced by the humming of the female.
It is said that 13,000 such olfactory organs are present on the feeler of a wasp, and 40,000 on the complex antennae of a male cockchafer.
The broad head carries, in addition to the prominent compound eyes, three simple eyes (ocelli) on the crown, while the feeler consists of a stout basal segment, followed by five slender segments.
They have eleven segments to the feeler, which is clubbed at the tip, and apparently three segments only in each foot.
A, Male; e, female; c, larva, magnified 20 times; b, foot of male; d, feeler of larva, more highly magnified.
If he were serious, it can only be said that the desperation of his circumstances had momentarily troubled the lucidity of his understanding; if the pamphlet were merely intended as a feeler after public opinion, it is surprising that he did not perceive how irretrievably he was ruining his friends in the eyes of all moderate men.
The families Psyllidae (or " jumpers ") with eight or ten segments in the feeler and the Aleyrodidae (or " snowyflies ") distinguished by their white mealy wings, are of comparatively slight importance.
Times (eyes, feeler, feet and e, Lacinia or " pick " of first claws more highly magnimaxilla.
This connexion feeler; e,of eye; b, brain.