THE OLFACTORY SENSE OF COLEOPTERA. 44I 



seconds, average 7.8 seconds; oil of thyme, 2 to 15 seconds, aver- 

 age 4.8 seconds; oil of wintergreen, 3 to 60 seconds, average 21.1 

 seconds. Five failed to respond to this odor. Leaves and stems 

 of pennyroyal, 5 to 60 seconds, average 32.2 seconds. Ten failed 

 to respond to this odor. Leaves and stems of spearmint, 3 to 60 

 seconds, average 29.8 seconds. Eight failed to respond to this 

 odor. Parts of decayed beetles, 3 to 60 seconds, average 30.4 

 seconds. Eight failed to respond to this odor. The general 

 average reaction time of the 25 beetles tested to the six odors is 

 22.7 seconds. In the wire-screen cage with the other potato 

 beetles already tested, these mutilated ones appeared normal, 

 because they ate normally and copulated as much as usual. 

 Since the soft dorsal sides of their abdomens were unprotected, 

 many of them soon began to sink, so that by the time a beetle 

 died, the abdomen had shrunk to about one-fourth its original 

 size. Up to the time of this writing (Jan. 15), 29 of these 31 

 mutilated insects have died. They lived from 3 to 140 days with 

 52 days as an average. 



(c) Effects with Elytra Pulled Off, Bases of Wings Glued and Pores 

 on Legs Covered with Vaseline. 



Twenty-nine more potato beetles were collected. Their elytra 

 were pulled off at the articulations. Two days later the upper 

 surfaces of the bases of the wings of the 26 remaining live ones 

 were covered with liquid glue. Since the olfactory pores extend 

 a considerable distance from the base of the wing along the 

 radial vein, the glue applied probably did not cover more than 

 90 per cent, of the pores on each wing. Three hours after apply- 

 ing the glue, the trochanters, femurs and proximal ends of the 

 tibiae of these beetles were covered with the vaseline-beeswax 

 mixture. An hour still later the insects were tested with the six 

 odors. They were as active as unmutilated ones and appeared 

 normal in all respects except in their responses to odors. Their 

 responses were never pronounced and seldom prompt. 



Their reaction times are as follows: Oil of peppermint, 3 to 60 

 seconds, average 10.7 seconds. One failed to respond to this 

 odor. Oil of thyme, 3 to 60 seconds, average 9 seconds. One 

 failed to respond to this odor. Oil of wintergreen, 5 to 60 seconds, 



