The potential for rootworm larvae to move between weeds within or adjacent to a maize field may be important in resistance management of transgenic-rootworm maize than initially envisioned. A study was conducted to determine how feeding by western corn rootworm larvae, Diabrotica virgifera virgifera LeConte, on alternate hosts followed by movement to transgenic maize plants impacts the development of the rootworm. The study was conducted in a split-split-plot randomized complete block design experiment under growth chamber-greenhouse conditions. Two weed species, large crabgrass, Digitaria sanguinalis (L.) Scop, giant foxtail, Setaria faberi R. A. W. Herrm, and a maize hybrid, Zea mays L., containing the rootworm resistant Cry3Bb1 transgene as well as its near isoline were evaluated. Original host plants’ boxes were randomly assigned a 5, 10, or 15 d host switch date. Four weeks after planting, the original hosts were infested with fifty neonate western corn rootworm larvae per box. On the 5th, 10th, and 15th d after infestation contents from assigned original host plant boxes were placed in Tullgren funnels fitted with 60W light bulbs for extraction of larvae to boxes underneath containing either transgenic (Cry 3Bb1) maize or its isoline seedlings (final hosts). Beetle emergence varied significantly among the original hosts and also among the final hosts. Beetle emergence was not significantly impacted by host switch date. Reproductive fitness of the females produced from each treatment is also compared. The impact of western corn rootworm host-switch and its implications on the resistance management of transgenic maize are discussed.