Female A. domesticus exhibit variability in their phonotactic behavior. Some females respond to syllable periods (SPs) typical of the males’ calling song (CS; 50–70 ms), others respond additionally to CSs with shorter or longer SPs, outside the range of males’ calls. Other females are not selective to SP and respond to the full range of SPs. Nanoinjection of Juvenile Hormone III (JHIII) into the prothoracic ganglion increases phonotactic selectivity. Nanoinjection of chelerythrine chloride (a protein kinase C inhibitor) reduces the effect of JHIII. The L3 prothoracic interneuron responds selectively to the SP of the male’s CS and is proposed to be involved in controlling SP-selective phonotaxis. Prothoracic nanoinjection of JHIII increases selective responses of L3 which parallels its’ effects on phonotaxis. This increase in selectivity seems to result from a decrease in decrement, predominantly at the shorter and longer SPs. Such effects increase selectivity in response to the SPs that are most attractive phonotactically. The data support the hypothesis that processing by L3 contributes to the SP selective phonotaxis observed in this species. Data currently being evaluated suggest that chelerythrine chloride opposes the effect of JH III on L3’s SP-selective responses.