A survey of the lygus bug (Lygus hesperus Knight) population in the San Joaquin Valley of California for susceptibility to bifenthrin was conducted using the glass vial technique. Lygus collected from alfalfa hay were found to be the most susceptible to bifenthrin while those taken from treated seed alfalfa and cotton were less susceptible. There was considerable variation in susceptibility in lygus collected from different crops, from the various geographic locations and different times during the season. These differences appear to be related to Capture Insecticide-Miticide and/or other pyrethroid use in the area being sampled. The data showed that lygus susceptibility to bifenthrin declines following a Capture application but recovers later in the season if the population is relatively susceptible at the time of treatment. Treatment of tolerant populations may only exacerbate control problems with a pyrethroid. These results suggests that if pyrethroid applications, including Capture, are restricted to once per season in a specific geographic area, susceptibility of lygus to Capture can be maintained. The data also suggest little long range lygus movement during the season.