78 



AN INTRODUCTION TO ENTOMOLOGY 



many jointed; while in others they are short and not segmented. 



The function of the cerei is different in different insects; they are 

 beHeved to be tactile in some, olfactory in others, 

 and in some males they aid in holding the female 

 during copulation. 



The median caudal filament.^ — In many of the 

 Ephemerida and in some of the Thysanura, the last 

 abdominal segment bears a long, median filament, 

 which resembles the many-jointed cerci of these 

 insects (Fig. 91); this filament is believed to be a 

 prolongation of the tergum of this segment and not a 

 true appendage lilvc the cerci. 



The prolegs of larvae. — The question whether the 

 prolegs of lan-ae represent true appendages or are 

 merely h^^Dodermal outgrowths has been much dis- 

 cussed. Several embryologists have shown that in 

 embry'os of Lepidoptera and of saw-flies limb-rudi- 

 ments appear on all or most of the abdominal seg- 

 ments; and that they very soon disappear on those 

 segments which in the lan^a have no legs while on other segments 

 they are transferred into functional prolegs. If this view is estab- 

 lished we must regard such prolegs as representing primitive abdo- 

 minal appendages, that is as true abdominal legs. 



Fig. 91. — Lepis- 

 ma saccharina. 



V. THE MUSIC AND THE MUSICAL ORGANS 

 OF INSECTS 



Much has been written about music; but the greater part of this 

 literature refers to mtisic made by man for human ears. Man, how- 

 ever, is only one of many musical animals; and, although he excels 

 all others in musical accomplishments, a study of what is done by our 

 humbler relatives is not without interest. 



The songs of birds command the attention of all observ^ers. But 

 there is a great orchestra which is performing constantly through the 

 warmer portions of the year, which is almost unnoticed by man. 

 Occasionally there is a performer that cannot be ignored, as: — 



"The shy Cicada, whose noon-voice rings 

 So piercing shrill that it almost stings 

 The sense of hearing." (Elizabeth Akers.) 



But the great majority fiddle or drum away unnoticed by human ears. 



