The wasps are now trapped between the two panes. The window has a lower and upper level and they are stuck in the upper part. They can't squeeze through, so my house isn't being over run at the moment. I can't reach the nest with the spray from below when I open the window (hard to explain). So I was thinking I'd have to put a "bomb" there to get the bastards.
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Ah...trapped between the panes.
Actually, this provides a tactical advantage: they probably won't be able to complete the classic bell shaped enclosure so the nest interior will remain exposed.
I've dealt with this situation. To eliminate a nest in this configuration, I waited till night (this is key since the nest will be least active and all workers will be back at home). I used a flashlight with red cellophane covering the light to illuminate my work -- the muted red is important, because a full strength light will arouse them. I suited up with Tyvek, including taped gloves and full bee suit head covering (if you can't get your hands on this sort of gear, dress fully in the heaviest clothes you have and wear protective eye wear (real safety glasses), real work gloves and a hat. Not really ideal but better than shorts and a t-shirt.
I opened the interior window slowly, taped all but a small opening and, using an insecticide dust application wand (similar to a turkey baster, but longer and capable of streaming agent with great force) doused the nest with Carbaryl (SEVIN).
The same procedure was repeated for two more nights, till all hornets were dead (including, most critically, the queen).
Needless to say, it's important to not fuck around and half-step this sort of thing. So, if you don't feel completely confident I'd call a pro (actually, maybe even if you do).
As for 'bombing'...
The problem is that most 'bombs' -- such as Raid foggers - are really broad area effect insecticide sprays. In your situation, you'd have to open the window pretty wide (certainly wider than a crack) to slide the can in; there's no guarantee you'd deploy it effectively. Also, most bombs are designed to kill roaches, silverfish, fleas and similar critters. Hornets and wasps, who're felled by chemicals rated by their dielectric potency*, are generally unaffected by these chemicals in their normal concentrations (one day, I'll tell the story of the former girlfriend who fearlessly sprayed a paper wasp nest with roach spray...an assault which prompted the wasps to take out their hankies, wipe their faces, point at the woman in the booty shorts and attack).
* <http://en.wikipedia.org/wiki/Dielectric_strength>
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