OLFACTORY ORGANS OF LEPIDOPTERA 



-EPg 

 PPg- 



53 



Fig. 10 Antennal organs of the geometrid moth, Fidonia piniaria, copied 

 from Schenk ('02). A, ventral view of terminal segment of male antenna, show- 

 ing disposition of pit pegs (PPg), end pegs (EPg), supported on the styles (St), 

 bristlelike hairs (Br) and ordinary hairs (Hr) in solid black, X 145; B, longi- 

 tudinal section through a pit peg, X 570; C, two end pegs, supported on a style, 

 X 220; D, section of a bristlelike hair, X 220; and E, longitudinal section of 

 three ordinary hairs, one-half schematic. Br, bristlelike hair (Sensilla saetica) 

 on antenna; EPG, end peg (S. styloconica) on antenna; Hr, hair, called S. tri- 

 chodea on antenna; Hr\ pseudo-hair in pit peg; iV, 'nerve; PPg, pit peg (S. 

 coeloconica) on antenna; SC, sense cell; SCG, sense cell group in antenna; St, 

 style supporting end peg. 



pit pegs and end pegs vary slightly in structure. The pit pegs 

 sometime consist of compound pits instead of single pits, and the 

 shape of the styles supporting the end pegs vary more or less. 



Since the peripheral ends of the sense fibers are covered with 

 the hard chitin forming the walls of all the antennal organs, it 

 does not seem reasonable that the outside air carrying odoriferous 

 particles can pass through the chitin in order to stimulate the 

 nerves within. 



