I want plans to build a Bug Detector?

Nigel finds a Tyrannosaurus track in volcanic ash, and sees by the dragged toes that it is the female with the gored thigh. Nigel sees that the Tyrannosaurus is walking alongside a river following a drifting Triceratops carcass. The carcass gets stuck in rocks in the riverbed. The Tyrannosaurus tries to reach the carcass, but mistrusts her footing among the loose wet rolling riverbed rocks and backs off. Nigel and others builds a crude stockade wall alongside the river, out of local Cretaceous fallen timber, trying to get the Tyrannosaurus to follow between the river and the stockade and thus through the time portal. A flock of Ornithomimus appear and run ahead, and the Tyrannosaurus chases them through the time portal into the park, where they cause surprise, but the Tyrannosaurus catches a straggler,a young Ornithomimus very near Nigel and turns back from the chase and does not reach the time portal. Instead of eating it there, she carries it a long distance into rough lava rock near the volcano despite her injured thigh. Nigel wonders why and follows her.