154 

 tetramers, and esterification products) produce ions which allow complementary 



confirmation of lactic acid presence. Additionally, the chloride attachment ions can 



be used for confirmation of lactic acid. 



Altering Attraction 



The addition of acid or base to lactic acid solutions was found to alter the 

 attraction oiAe. aegypti to the sample. These effects presumably occur through the 

 acid dissociation equilibrium. Addition of acid shifts the equilibrium towards the 

 formation of the volatile associated acid form. Addition of base shifts this 

 equilibrium towards the involatile dissociated lactate anion. Examination of similar 

 solutions to those employed in the acid/base lactic acid study revealed that methyl 

 lactate was formed while in methanolic solution. Subsequent testing of lactic acid 

 esters and a similar ester revealed that lactic acid provides greater attraction than the 

 esters. It was also found that addition of acid enhanced mosquito attraction in all 

 cases. 



Origin of Attraction 



The data presented support the view that excess perspiration masks attraction 

 by hindering volatility off the skin of lactic acid and other possible attractants. These 

 data also show that the lactic acid signal from direct dissolution of perspiration in 

 methanol is diminished compared to analyses with one or more glass beads. This 

 confirms the very dilute nature of perspiration, and that handling glass transfers a 



