The Asian woolly hackberry aphid, Shivaphis celti Das (Homoptera: Aphididae), was first detected infesting Celtis species in California in 2002. The copious honeydew produced by the aphid and the black sooty mold it promotes are nuisances that often require treatment. Aphid and predator populations were monitored for three seasons and aphid densities were found to be highest in the spring and fall with lower densities during the mid-summer months. A method of monitoring honeydew production using water sensitive cards was found to consistently and efficiently reflect aphid populations and may be used to define treatment thresholds. Imidacloprid as a soil applied systemic insecticide provided effective season long aphid control in field situations. Results will also be presented from the 2005 field season when early season treatments were compared to treatments applied mid season and at varying rates.