Effects and Control of Periodical Cicada Magicicada Septendecim and Magicicada Cassinioviposition Injury on Urban Forest Trees

The long-term effect of oviposition by the female periodical cicadas, Magicicada septendecim and M. cassini (Homoptera: Cicadidae) was examined on shade trees at two urban forest sites in northeastern Illinois following the 1991- 1993 growing seasons. Minimum branch diameter appears to be a critical factor in ovipositional activity. Plants with stout branching habits do not appear to be suitable for oviposition. Percent canopy flagging, as a function of the number of wounds per branch, may not be an accurate measurement of ovipositional damage. Young trees with stem diameters or main scaffold branches with diameters between 5 and 10 mm may experience significant damage to the main trunk resulting in breakage and significant growth loss. Larger plant material does not appear to be significantly affected by ovipositional damage, which results only in a minor natural pruning event. Chemical control for the prevention of ovipositional wound damage by the female periodical cicada does not appear to be a practical and effective pest management option. Even severe and heavy ovipositional damage does not appear to predispose urban forest trees to attack by secondary insects or pathogens.