Twenty-one halo- and cyanopyrroles related to the trail pheromone of A. texana, Methyl 4-Methylpyrrole-2-carboxylate [34402-78-3], were prepared and tested by a faster and more sensitive bioassay than was previously available. Methyl 4-Chloropyrrole-2-carboxylate [1194-96-3] and Methyl 4-bromopyrrole-2-carboxylate appeared to be as active as the first one. Responsiveness of the ants in descending order to these compounds based on the constituent in the number two position, was: esters, methyl ketones, aldehydes.
