Blissus insularis Barber is a key pest of St. Augustinegrass that has developed resistance to several insecticides. Implementing a successful resistance management program requires a thorough evaluation of insecticide efficacy and response of B. insularis to those commonly used. A new method for evaluating the contact and systemic activity of insecticides against B. insularis was developed. St. Augustinegrass plants (9 cm diameter) were treated with insecticides and allowed to dry for either 24 h (contact) or 72 h (systemic). Once dry, a single node was placed into each cell of a BioServe® tray with one 2-3 wk old adult, and mortality was examined at 1, 4, 8, 24, 48, and 72 h. Insecticides tested included bifenthrin, carbaryl, clothianidin, imidacloprid, and trichlorfon. Preliminary range testing was determined for each insecticide to establish mortality ranging from 5 to 95%. All bioassays were held in growth chambers at 25ºC and a photoperiod of 14:10 (L:D) h. Abbott’s formula was used to correct for control mortality. The LC₅₀ and LT₅₀ values, 95% fiducial limits, and slopes of the regression lines were estimated by logit analysis. This new bioassay more closely predicts the in-field efficacy of contact and systemic insecticides compared to previous assays, providing baseline information to monitor insecticide resistance development in B. insularis populations in Florida.