LAUSR

Abstract. The walnut twig beetle, Pityophthorus juglandis Blackman, and its fungal associate Geosmithia morbida Kolařík et al., produce thousand cankers disease, which has devastated black walnut (Juglans nigra L.) in several states of the western U.S.A. To better understand beetle flight dynamics and life history, flight times were documented in the urban corridor along the Colorado Front Range during 2 years -- in 2008 with yellow sticky card traps and in 2012 with baited multiple funnel traps. Walnut twig beetles were determined to be active throughout the trapping season from March through November, exhibited overlapping generations, and potentially a bivoltine life cycle. Most beetles were collected from traps between July and September, and the greatest trap density frequently occurred in August. The total number of beetles collected throughout the trapping season differed at each location. In 2008 the number of beetles collected ranged from 12 to 145, and from 60 to 12,909 in 2012. More beetles were found in municipalities experiencing early disease development when compared to cities with chronic disease.