498 THE SENSES AND SK.VSOR Y ORGANS. 



ahirmed by unwonted sounds, especially in the dark, and the 

 behaviour of Graber's blinded cockroaches was indicative of 

 fear whenever he produced sounds in their vicinity. Graber 

 has also shown that water insects, both Coleoptera and 

 Hemiptera, are readily alarmed by sounds. 



Lubbock has stated that Bees, Wasps, and Ants do not 

 apparently take any notice of sounds, but he admits that there 

 is evidence of their possessing the faculty of hearing. I am 

 certain that the large Myrmecias of Australia are excited to 

 take up a threatening attitude when a footfall is heard in the 

 forest, and it appears piobable that, in a country like England, 

 where noises are continually occurring, that all but the most 

 timid insects have probably long since learned to disregard 

 them. In the virgin forest the stillness is often oppressive, even 

 to man, and the slightest rustle amongst the foliage is very 

 often more startling than the unexpected firing of a pistol is in 

 a civilized country. 



It is only natural to conclude that insects which produce 

 sounds also hear them, and that the grasshoppers and crickets 

 take pleasure in their chirruping song ; but it is possible also 

 that the same sounds are pleasant to other insects. My friend 

 K. T. Lewis writes to me that a large lace-winged fly in Natal, 

 Xotochrysa gigantea, is said to assemble in numbers round the 

 head of a singing Cicada; it might be called the 'audience 

 insect,' and he tells me that one which he sent me for ex- 

 amination was caught with nine others flying round the head 

 of one of these insect songsters. 



The Olfactory Sense. The fact that scents are keenly per- 

 ceived by insects of certain species has been long known ; the 

 manner in which carrion-feeding insects discover a dead 

 animal, and the discovery of a female moth enclosed in a chip 

 box by numerous males of the same species, are well-known 

 examples of a keen power of scent. Briefly, us IVrrissays [266|, 

 ' that this sense is highly developed in the greater number of 

 Arthropods is a fact long ago established; for which there is 

 no longer need of argument or proof.' 



\Yitli regard to the localisation of the olfactory sense, how- 



