More thrips overwintering in Maryland

Md. Coop. Ext. IPM vegetable specialist Gerald Brust has been conducting a 2-year survey to determine if thrips overwinter. For most samples no thrips were found. In 5 of the 12 sample sites, thrips were found in December through January on winter annuals. Western flower thrips were found to overwinter in Maryland, Delaware and Virginia, although in low numbers. Chickweed was found to harbor 70% of all thrips; wild mustards and henbit were the next best winter hosts. Sampling sites near high tunnels or woods had a greater probability of containing thrips than open-field sites. Farms where thrips were found to overwinter had greater probabilities of infestations during the season.