Studies on the responses of the femaleAedes Mosquito. X.—Comparison of oestrogens and amino acids as attractants

The attractiveness of oestriol and of a sample L-lysine to females ofAedes aegypti(L.) was tested (a) in an olfactometer of the Wieting-Hoskins type, and (b) in a free-flight cage enclosed in glass. Similar results were given by both methods, L-lysine being the more attractive at higher concentrations, but oestriol retaining its attractiveness down to much lower concentrations. When 27 L-amino acids were tested in the free-flight cage, 16 showed significantly positive stimulation. Of these lysine was the most attractive, representing a group of 11 which carried CO2in carbaminoyl or adsorbed form or in both; the other five, of which tyrosine was the most attractive, carried no CO2.