A 2:1 mixture of Bacillus cereus and B. megaterium was topically applied to aerial plant parts of cotton. These bacteria were found to enhance the concentration of monoterpene compounds in air surrounding cotton flower buds 14 days after application. Additionally, pheromone in the air surrounding cultured boll weevils was increased when they fed on ICAMD-EL flower buds from bacterially treated plants. However, pheromone in the air was decreased when weevils fed on 'SP-37H' flower buds from bacterially treated plants. Bacterial applications to cotton plants altered secondary plant chemistry, and boll weevil pheromone production in a little understood manner.