Green peach aphid is the most important insect pest of potatoes and many other vegetables because of disease transmission to these crops. A better method to mark and recapture aphids was needed to identify the importance of weedy reservoirs of potato diseases and when these are used by alate M. persicae prior to arrival in new potato fields. We refined a method to mark aphids on weedy plants using an inexpensive protein marker (egg whites) which allows use to spray large areas. We also developed a dry trapping method suitable for recapturing the aphids that retains the mark. This method allow us recapture aphids and detect the mark using off-the shelf antibodies in ELISA.