THE OLFACTORY SENSE OF COLEOPTERA. 439 



of blood always exuded from each wound caused by the elytron 

 being pulled off, but only occasionally was blood seen where a 

 wing had been pulled off. A day later when tested with the 

 odors from the three essential oils, these beetles were compara- 

 tively quiet and they appeared normal in all respects except in 

 their slowness in responding to odors. 



Their reaction times are as follows: Oil of peppermint, 2 to 30 

 seconds, average 7.1 seconds; oil of thyme, 3 to 20 seconds, 

 average 8.9 seconds; oil of wintergreen 3 to 55 seconds, average 

 13.4 seconds. The general average reaction time to all three 

 odors is 9.8 seconds. In the cage with the other beetles, these 

 mutilated ones were as active as the unmutilated cerambycids 

 and they were often seen copulating with each other, and with 

 the unmutilated and antennseless ones. They lived from i to ii 

 days w4th 4.2 days as an average. 



CHRYSOMELIDiE. 



The Olfactory Sense of Leptinotarsa lo-lineata. 



Forty-five Colorado potato beetles {Leptinotarsa lo-lineata) 

 were collected in a potato patch near the laboratory. While 25 

 of them were being tested with the six odors, they were com- 

 paratively quiet as a rule, but five were so restless that they 

 were discarded and others were used. Their responses were 

 similar to those of Harpalus pennsylvanica, described on page 429. 



Their reaction times are as follows: Oil of peppermint, 2 to 7 

 seconds, average 3.3 seconds; oil of thyme, 2 to 5 seconds, average 

 3.1 seconds; oil of wintergreen, 2 to 12 seconds, average 5 seconds; 

 leaves and stems of pennyroyal, 4 to 60 seconds, average 26.7 

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

 of spearmint, 2 to 60 seconds, average 25.6 seconds. Seven failed 

 to respond to this odor. Parts of decayed beetles, 5 to 60 seconds* 

 average 27.9 seconds. Seven failed to respond to this odor. 

 The general average reaction time of the 25 beetles tested to all 

 six odors is 15.4 seconds. These insects were confined in a 

 cage in the light near a window. This cage is 30 inches long, 

 30 inches high and 4^ inches wide. All six sides are wire-screen. 

 A fresh supply of potato plant leaves was constantly kept in the 

 cage. The beetles confined in this cage on the potato plant 



