44 



AN ECONOMIC ENTOMOLOGY. 



and so keen is this sense that they discover the presence of the 

 female, even when confined in a breeding-cage, if a window be left 

 open. Sometimes male wood-borers will sit around a spot on the 

 bark for a considerable time awaiting the emergence of a female, 

 which their keen sense tells them is fully developed and ready to 

 make her way out. Carrion feeders discover their food when con- 

 cealed from sight, and almost before decay has set in. So far as 

 we have been able to ascertain, the olfactory organs are situated 

 in the antennae, and form small pits or depressions, from which 

 usually arise specialized hairs, bristles, or pegs, as the case may be. 



Fig. 23. 



Sensory organs of insects. — A, sensory pittings in plant-louse antennae; organ of 

 smell in May-beetle; C, same in wasp; D, sensory organs in Termes flavipes ; E, F, 

 organs of taste in a wasp ; G, organ of smell in grasshopper ; H, sensory depressions 

 on the tibia of Termes ; I, terminal joint of antenna of an ant ; K, section through the 

 antenna of a honey-bee, showing supposed olfactory- organs. All greatly enlarged. 



The sense of touch is located popularly, and I think correctly, in 

 the antennae ; but it is quite certain that tactile hairs exist all o\-er 

 the body of the insect, more developed in some than in others, 

 and most, perhaps, in larval forms. These structures always 

 consist of specialized hairs or bristles, and end in a nerve cell. 



