Centrifuged and filter-sterilized salivary homogenates of male and female cotton fleahoppers (CFH),Pseudatomoscelis seriatus(Reuter), were found to contain a polygalacturonase (pectinase), an enzyme capable of breaking down pectic materials in the middle lamella of plants. Salivary preparations from male CFH had more enzyme activity than homogenates from female salivary glands. Salivary extracts were strong elicitors of stress ethylene production when injected into excised cotton shoot tips. Excised cotton buds injected with male salivary preparations produced ethylene at higher rates than those buds injected with female preparations. Enzyme activity and ethylene-inducing capacity of these salivary homogenates were destroyed by boiling and reduced by long-term storage. Ethylene production by cotton buds also was induced by solutions of commercial pectic enzymes.