Tracking technology has advanced to the point that some devices are small enough to be attached to bumble bees (such as this Bombus terrestris), though battery-powered devices remain too big for all but the largest of insects. The transponder on this bee is unpowered and weighs about 15 milligrams (while battery-powered units weigh about 200 mg) and can be tracked using harmonic radar. (Photo credit: Wikimedia Commons/Andrew Martin, CC BY 2.5)