A solution. There's things called mosquito coils, which you burn. A coil is about the size of your palm, and the instructions say to leave it burning, but in fact you only need an inch of coil for a 2-person tent, or maybe a couple of inches per compartment in a frame tent. We bought a pack of this stuff for use in Scotland against the midges, and we maybe used a coil in a fortnight (box contains 6 coils IIRC for £5).

The plan is, you get into your tent (along with insects), zip everything up, and then light the coil. It doesn't flame, but you don't want hot ash burning the groundsheet; best plan is to rest it on a fork (or on the little stand they provide), inside a billycan lid. 10-15 minutes later, the stuff's burned down, the tent's got this joss-stick smell (the smell gets right into your clothes and sleeping bag BTW), and all the insects that came in with you are dead. As Gary says though, if the tent inner doesn't have an integral groundsheet and the zip doesn't close, you're SOL. This stuff doesn't smell too good, and it kills insects, so you probably don't want to leave a coil burning away in an enclosed space like a tent.

It also helps to deter insects in less sealed environments. In a villa in Greece, we used about half a coil per room per night, in a high-ceilinged villa, which didn't stop all the mossies but certainly reduced the number of bites.

Why bother with daddy-long-legs though? They're easy to catch and return outside. Failing that, a newspaper is effective.

Graham.