Potato virus Y (PVY) is a nonpersistent, stylet-borne virus, transmitted by over fifty aphid species.  Aphids determine host suitability with quick, brief intracellular probes which can result in acquisition and transmission of PVY.  As an aphid probes epidermal tissue, virus is deposited.  After a few probes, the aphid can no longer transmit and must reacquire the virus to remain infective.  Monitoring of aphid probing on potato was accomplished with electronic penetration graphs (EPG).  Intracellular punctures were marked as potential drops.  Others have shown that potential drops are necessary for transmission of nonpersistent viruses and that the frequency of potential drops determines transmission efficiency.  Previous work by this group has shown that Aphis glycines Matsumura can transmit PVY to potato at 33% efficiency.  In comparison, the most efficient vector of PVY, Myzus persicae (Sulzer) transmitted at 100%, Macrosiphum euphorbiae (Thomas) at 87% and Rhopalosiphum maidis (Fitch), a poor vector, did not transmit PVY in our studies.  To determine if transmission efficiency was correlated with probing behavior, experiments were conducted using a Giga 4 EPG to measure the frequency of probes by each aphid species within 15 min, a typical acquisition access period given aphids in virus transmission studies.  Time to 1^st probe, time to 1^st potential drop, and number of potential drops were recorded using WinDaq Lite software.  Preliminary data indicated that A. glycines probed less frequently than M. persicae and A. glycines probed even less frequently when starved.  This suggests that probing behavior affected PVY vector efficiency.