[21] Newport, _The Antennæ of Insects_, Entomol. Society, Vol. II.
Will put a female Cerambyx beetle into a box, which he placed on a table; he then put a male Cerambyx on the table, some four inches from the box. When he touched the female she began to chirrup, whereupon the male turned his antennæ toward the box, "as if to determine from which direction the sound came, and then marched straight toward the female." Will concluded from this that the ears of the beetle were located in its antennæ.[22]
[22] Will, _Das Geschmacksorgen der Insecten_, Wiss. Zool.; quoted also by Lubbock, _Senses, Instincts_, etc., p. 96.
Seeing that Will's experiment as described by him was incomplete, I took a pair of beetles belonging to the same family (genus _Prionus_), and determined the true location of their ears by a system of rigid exclusion. These beetles, when irritated, make a squeaking chirrup by rubbing together the prothorax and mesothorax.
When I irritated the female she began to chirrup, and the male immediately turned toward the small paper box in which she was confined. I then removed the antennæ of the male, and again made the female stridulate; the male heard her, and at once crawled toward her, although his antennæ were entirely removed.
This showed conclusively that the organs of audition were not located in the antennæ, as Will supposed and as Lubbock advocates. I then removed the maxillary palpi of the male, after which the insect remained deaf to all sounds emanating from the female.
Again, I took an unmutilated male, which at once turned and crawled toward the chirruping female. I then removed its labial palpi, leaving maxillary palpi and antennæ intact; it heard the female and made toward her. The maxillary palpi were then removed (the antennæ being left _in situ_), and at once the creature became deaf.
If the maxillary palpi of long-horned beetles be examined, certain vesicular organs, each containing a microscopic hair, will be observed in the basal segments; these, I take it, are auditory vesicles. In some of the Coleoptera I have found auditory rods in the apical segments, though this is by no means a common occurrence. In Cicindelidæ and Carabidæ these auditory vesicles are exceedingly small, and require a very high-power objective in order to be clearly seen.