Association of Scolytus Ventralis (Coleoptera: Scolytidae) and Phoradendron Bolleanum Subspecies Pauciflorum on Abies Concolor

Attacks by Scolytus ventralis on white fir were correlated both with periods of low precipitation and with medium to heavy infestations of true mistletoe. Trees were seldom attacked when the "running mean precipitation" was above 54 in. Attacks were significantly more frequent and were often a year or more earlier on trees with substantial amounts of mistletoe. Broods were seldom produced, however.Data suggest that heavy mistletoe infestation rendered trees more susceptible to beetle infestation, possibly by creating moisture stress in infected trees.