THE SPECIAL SEXSES 



Many larval forms, such as caterpillars and others 

 which move about in quest of food, possess simple eyes 

 in varied numbers. 



Just how well and how accurately insects can see, is 

 still an open question. It is evident that insects can 

 perceive objects in motion better than at rest. Anyone 

 who has ever disturbed a bumblebee's home, or a hornet's 

 nest, knows that, though in a comparatively safe place, ;i 

 movement on his part is 

 likely to lead to his dis- 

 covery and bring down 

 the wrath of some scout- 

 ing bee. It is probable, 

 then, that the principal 

 use of the compound 



FIG. 29. Illustrating mode of vision in a 

 eye IS tO perceive, not many-faceted eye. (After Lubbock.) The 



the form, but the move- "f* h ente " lrough cornea - , The rays 



which strike the sides of each tube or cone 



ment of oblOCtS. It IS are absorbed by the black pigment which 



, 11'' surrounds each tube. Accordingly, those 



further believed that 111- rayg O f nght only which pass through the 



sects cannot clcarlv per- ^ 8tal ne cones dire f * ^ ?**? 



from their sides), such as a-a , b-b , c-c , 

 CeiVC oblCCtS at a (lis- d-d', e-e', will ever affect the nerves at ', 



6', c', d', e . According to Lubbock, the 



tance greater than SIX larger and more convex the eye, the -wider 

 / 1 ,i ,! will be the field of vision ; while the smaller 



feet away, and that with andmorenumerous are the facets , the more 



few exceptions, SUch as distinct will be the vision. 



the dragon-fly and honey-bee, insects are guided rather 

 bv the sense of smell than that of siirht. 



> o 



The Sense of Hearing.- -The location of the auditory 

 organ in the grasshopper (Fig. 20:5, E, and.} is on 

 the side of the insect immediately back of the thorax. 



/ 



The oystershell-shaped covering is simply a highly at- 

 tenuated and fully stretched portion of the body cover- 



