Waveforms from AC and DC electronic monitoring systems were directly compared to determine which waveforms were equivalent to one another. Comparisons were facilitated by a device that allowed rapid switching from system to system while an aphid was producing a given waveform. Results revealed that potential drops occur in AC systems and that X waves occur in DC systems. For reasons presented, we propose that the term stylet pathway phase replace salivation, that sieve element phase replace phloem ingestion, and that nonphloem phase be used in AC systems instead of nonphloem ingestion. In general, the DC system could distinguish more details than could the AC systems we used.