Several halo- and cyanopyrroles related to the trail pheromone ofAtta texana(Buckley), were prepared and tested by a faster and more sensitive bioassay than was previously available. Responsiveness of the ants in descending order to these compounds, based on the substituent in the number two position, is: esters, methyl ketones, aldehydes. Slight activity was observed when the nitrogen atom of the pyrrole ring was alkylated.