442 N. E. MCINDOO. 



average 35.9 seconds. Eleven did not respond to this odor. 

 Leaves and stems of pennyroyal, 3 to 60 seconds, average 35.2 

 seconds. Twelve did not respond to this odor. Leaves and 

 stems of spearmint, 5 to 60 seconds, average 42.6 seconds. Four- 

 teen failed to respond to this odor. Parts of decayed beetles, 

 5 to 60 seconds, average 40.3 seconds. Fourteen failed to 

 respond to this odor. The general average reaction time of the 

 26 beetles tested to the six odors is 29 seconds which is twice the 

 reaction time of unmutilated potato beetles to the same odors. 

 When the reaction times to the odors from only the three essential 

 oils are considered, these mutilated insects responded only one 

 fifth as rapidly as did the unmutilated ones. In the wire-screen 

 cage with the other potato beetles already tested, they were 

 apparently normal as long as they lived, because they ate and 

 copulated as usual and were always as active as the unmutilated 

 ones. Before they died their abdomens shrunk considerably in 

 size. Up to the time of this writing (Jan. 15), 28 of the 29 have 

 died. These lived from 2 to 151 days with 61 days as an average. 



MELOID^. 



The Olfactory Sense of Epicauta marginata. 



Twenty blister beetles {Epicauta marginata) , commonly known 

 as the "old-fashioned potato bugs," were caught on clematis. 

 When mechanically irritated, they fold the antennae and legs 

 against the body, usually eject a small drop of amber-colored 

 liquid from each femoro-tibial articulation, and feign death. 

 On account of this behavior, they were unsatisfactory to experi- 

 ment with. When put into the experimental cases, some of them 

 lay apparently lifeless for almost a half day. In this state they 

 never respond to any odor, and after becoming as active as usual, 

 they may or may not respond to odors. 



When tested with the odors from only the three essential oils, 

 a general average reaction time of 13.9 seconds was obtained. 

 Two of them failed to respond to each of the oils of peppermint 

 and wintergreen. These insects were confined in the cage 

 described on page 436. They were regularly provided with a 

 fresh supply of clematis. In this cage on the clematis they 

 seemed "at home," but they flew out at every opportunity. 



