After the first shot ran out, the rangers had picked up their own rifles and took aim taking aim and scanning the area for the shooter, while after the second shot rang out and killed the driver, the ranger in the passenger's seat screamed, then lowered his rifle and reached for the steering wheel to keep the jeep under control, leaving the two rangers in the back with their rifles aimed. Unfortunately for them, they were looking for a human marksman shooter, not an alien, whose relatively small size and camouflage kept it from being noticed.
Seeing the ranger in the passenger's seat going for the wheel, and not wanting to let its target get away, the bug first tried to aim for the ranger that held the wheel, but couldn't get him in its sights due to the angle. Instead, the bug calculated where the jeep's front tire would be with its current speed and the direction it went it, and adjusted its aim accordingly, taking a shot once the tire came within its sights, popping it.
While loading the next round, the bug raised its head to one of the rangers in the back, noting he had spotted it due to the noise of its shot. Calculating where the ranger would be, while taking into acount the direction of the wind, the bug shot a glob of glue at him, the adhesive projectile largely hitting the ranger in the face.
This made the ranger stumble backwards and bump into the other ranger who was riding in the back, knocking him off balance. Taking this oppertunity, the bug took aim at the ranger that was thrown off-balance, and fired. The shot hit, throwing the ranger down, but wasn't imediately fatal, the bullet hitting the collar bone. With the rangers either occupied or disabled, the bug dropped its rifle and leapt out of the grasses and sprinted after the jeep, catching up to it easily enough. Moving itself behind the jeep, the bug leapt up, latching on to the open frame.