24 



INTRODUCTION. 



the air, instead of removing them. Experiments performed on 

 insects of various orders gave much the same results. Some lived 

 for months, without apparently suffering inconvenience, after the 

 extirpation of the antennae, while others died in a few days. In 

 all cases, however, they appeared to have lost the sense of smell 

 only. Experiments bearing on the use of the antennae in seeking 

 food were also made with Silpha and certain flesh-flies. The 

 strong-smelling food was only discovered by the insects while in 

 possession of antennae ; without them they failed to localise it. 

 Bolboceras (Geotrupid^e) has been observed unerringly discovering 

 truffles, and this it must do by the aid of smell, as they are found 

 at some distance underground. 



The actual organs of smell appear to consist in most cases of pits 

 on the antennae connected with, nerve rods and a ganglion cell ; 

 they are not, apparently, so numerous or important in the 

 Coleoptera as in other orders, yet they are found distinctly in 

 Silpha, Necrophorvs, Staphylinus, Philonthus, Tenebrio, and the 

 Lamellicornia. According to Arrow (Eauna Brit. Inch, Col., 

 Lamell., i, p. 1) the apposed faces of the fan-like leaves or lamellae 

 in the last-named group are furnished with minute sensory pits 

 and hairs which are freely exposed to the air when the beetle is 

 in motion. Smell and hearing therefore, if such senses exist, are 

 probably well developed in the antennae of the Lamelltcornia. 

 The sensory pits have not yet been satisfactorily traced in the 

 Carabib^;, Cerambycid^e, CuRCULioNiDiE, Chrtsomelid^e, or 

 Meloid^e. It is probable that other olfactory organs exist on 

 the palpi or other portions of the head or body of various insects. 



The organs of taste appear to consist of very small pits or cups or 

 of hair-like or peg-like setae situated on the epipharynx, which 

 have been proved by Will and others to be connected with gang- 

 lionated nerves. These are very generally distributed in the 

 Coleoptera, and occur not only in the adult beetles, but also in 

 the larvae of several groups. The taste organs of the CicindeliDtE 

 differ entirely from those of the Carabid.e, and are peculiar to 

 the group. In the latter family they are well developed, as they 

 are also in the Dytiscid^e, the Phttophaga, and the Scolytid^e. 

 In the Bi'PRES/riDiE no true taste cups have been detected ; in the 

 ScaraBjEId^e they occur in some instances and not in others ; 

 while in the Longicornia they are always found without any 

 known exception. 



The organs of hearing. — The fact that Coleoptera produce sounds 

 by stridulation, tapping, etc., seems to prove that they must possess 

 auditory organs of some sort. It must, however, be allowed that 

 Huber, Perris, Eorel, and other authorities deny their existence, 

 claiming that the so-called "hearing" is merely tactile. The 

 various stridulating contrivances will probably be noted by writers 

 on the different groups, as they are occasionally very useful 

 characters in classification, e. g., in the Longicornia, in certain 

 Erotyub^e (Languriuv.e), etc. A good account of these organs, 

 so far as they were then known, is given by Darwin (Descent of 



