The Structure and Special Physiology of Insects 29 



distances spon found their way to the jar (containing females) which had 

 its mouth open to the air, but no male came to the jar with its mouth her- 

 metically sealed. Through the glass sides of both 

 jars the females were plainly visible. The antennae 

 of certain males were covered with shellac. These 

 males, when released, never found the females, and 

 often paid no attention to them when brought within 

 an inch of their bodies. Of other males the eyes 

 were covered with pitch; but these males had no 

 difficulty whatever in finding the females. It is 

 plainly obvious from these experiments that the 

 males found the females wholly by scent and not at 

 all by sight. 



That some insects hear is proved by their posses- 

 sion of auditory organs, and has also been demon- Fig. 56. — Male mosf|uito, 



strated by experiment. The fact, too, that manv f "'"'"S ("^''■' 'in"'"":'! 

 J c ' > ,' hairs. (.'Vftcr Jordan 



insects have special sound-making apparatus and and Kellogg; three times 

 do make characteristic sounds is a kind of proof natural size.) 

 that they can also hear. The auditory organs of insects, curiously enoup;h, 

 are of several kinds and are situated on different parts of the body, in 



various species. Among the locusts, 

 katydids, and crickets, the most con- 

 spicuous of all the sound-making in- 

 sects except the cicada, the ears are 

 small tympanic membranes on the 

 base of the abdomen in the locusts 

 (Fig. 55), and on the tibiae of the fore 

 legs in the katydids and crickets. 

 Associated with each tympanum is a 

 small liquid-filled vesicle and a special 

 auditory ganglion from which an 

 auditory nerve runs to one of the 

 ganglia of the thorax. Among the 

 Fig. 57.-Diagram of longiludinal section midges and mosquitoes the antennae- 

 through first and second antennal scg- those all-important sensitive structures 



ments of a mosquito, Mochlonvx ciilici- u i .i 'A a nu „ ■ 



, • „ , 1 • „ 1 ' 1-, „, — are abundant y provided with cer- 



jormis, male, showing complex auditory ■ r 



organ composed of fine chitinous rods, tain fine long hairs, the auditory hairs 



nerve-fibers and nerve-cells. (.\fter .p- gx .^^.j^j^j^ j^j.^ ^^^ 'ix^uM- 



Child; greatlv magnified.) v o j /> i _ 



waves and transmit the vibrations to an 



elaborate percipient structure composed of many fine chitin-rods and ganglion- 



ated nerves contained in the next to basal antennal segment (Fig. 57). From 



this segment runs a principal auditory nerve to the brain. JNIany other insects 



