THE OLFACTORY SENSE OF COLEOPTERA. 43 1 



ones and buried in the earth as usual. Seven days later they 

 were placed singly into the experimental cases and were tested 

 with the six odors as usual. They wandered about in the cases 

 slightly more than did the unmutilated ones, but when tested 

 they gave similar responses and reacted just as promptly. 



Their reaction times are as follows: Oil of peppermint, 2 to 15 

 seconds, average 3.8 seconds; oil of thyme, 2 to 25 seconds,, 

 average 4.7 seconds; oil of wintergreen, 2 to 25 seconds, average 

 6.9 seconds; leaves and stems of pennyroyal, 3 to 50 seconds,. 

 average 14.4 seconds; leaves and stems of spearmint, 3 to 60 

 seconds, average 34.9 seconds. Ten failed to respond to this 

 odor. Parts of decayed beetles, 3 to 60 seconds, average 32 

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

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

 is 16.1 seconds. Up to the time of this writing (Jan. 15), 23 

 of these beetles have died. They lived from 19 to 171 days 

 with 58 days as an average. 



(b) Effects with Elytra and Wings Pulled Off, 



The elytra and wings of 25 Harpalus pennsylvanica, just 

 collected from the cornfield, were pulled off at their articulations. 

 These mutilated insects were then put into a third box, similar 

 to the two already described. The box was kept in the table 

 drawer with the others. On the following day after mutilating, 

 the beetles, they were placed singly into the experimental cases 

 and were tested with the six odors as usual. They seemed 

 normal in all respects except they were extremely restless. 

 Their responses to odors were similar to those of unmutilated 

 ones, except they were slower. 



Their reaction times are as follows: Oil of peppermint, 3 to 45 

 seconds, average 10.7 seconds; oil of thyme, 5 to 50 seconds,, 

 average 10.2 seconds; oil of wintergreen, 5 to 60 seconds, average 

 18 seconds. Two failed to respond to this odor. Leaves and 

 stems of pennyroyal, 5 to 60 seconds, average 29.2 seconds. 

 Seven failed to respond to this odor. Leaves and stems of spear- 

 mint, 5 to 60 seconds, average 24.7 seconds. Four failed to 

 respond to this odor. Parts of decayed beetles, 5 to 30 seconds, 

 average 13.4 seconds. The general average reaction time of the 



