I concur from what little information has been given that these 'large' wasps are probably drones. As Gregior quite rightly says drones have a long abdomen (an extra segment compared to females) and long antennae. It's unusual for drones to get caught in traps which suggests that there may be some environmental stressors at play in your location forcing them out of their nests prior to them embarking on their mating rituals. The bad news is that this is another sign that wasps will start sweet feeding on mass pretty soon.
The sexual progeny of Dolichovespula media are pretty large and quite fearsome but the workers aren't much bigger than Vespula germanica and aare usually quite dark in colour with narrow yellow bands. It sounds as though Toby you have treated median nests just as they are maturing and full of queens and drones. Queen media wasps look very similar in appearance to hornets. Again this is another sign that things will be hotting up pretty soon.