Identification and monitoring of the red clover casebearer moth (Coleophora deuratella) in clover seed crops in western Oregon

The red clover casebearer, Coleophora deauratella Leinig and Zeller (Lepidoptera: Coleophoridae), is native to Europe, eastern Siberia, and the Middle East. Its original introduction into eastern North America likely occurred in the early 1960’s. The distribution of C. deauratella in North America was thought to be restricted to the north-eastern United States and southeastern Canada until it was discovered on red clover in Alberta, Canada in 2006 where it has since become a significant pest of clover grown for seed. The first identification of this pest in the western United States was made in Oregon in red clover seed fields in 2012.  A pheromone-based monitoring program was subsequently established in western Oregon to determine the presence and seasonal activity of adult C. deauratella in clover seed fields. In 2013 and 2014 pheromone-baited traps were placed in eight commercial red clover, Trifolium pretense L., seed fields and three commercial white clover Trifolium hybridum L., seed fields.  Green Unitraps were baited with gray septa lures placed 35 cm above the soil surface and at least 5 m from the field edge and number of moths per trap were monitored weekly for 14 weeks from early May to early August. At peak bloom (BBCH growth stage 65) 100 mature inflorescences and 100 immature inflorescences were sampled and evaluated for floret damage caused by C. deauratella. An average of 98 male adults were recorded per trap each week in red clover fields, while only five male adults were found weekly in traps located in white clover fields. The number of adults recorded was greatest in the months of June and July. Higher numbers of adults were found in second and third year red clover fields compared to first year fields. Larval feeding damage was recorded in only 80 florets per 1000.  These results indicate that C. deauratella is present in western Oregon and favors older red clover plants over white clover. It does not appear that economic crop damage is occurring at present.