In reply to Caucasus Gulag Inmate:
Was in South Greenland last year for 4 weeks.
Mosquito's certainly were around (but not in great numbers), but none were present once you got higher up.
By far the biggest pest (ignoring the arctic fox that decided to have a "territorial battle" with us - well we did start it!!) was black fly. Even in light rain and winds the beggers would still come after you!!
The mosquito's typically attack under cover of the black fly, which can make them a problem outside the tent! But at least their distinctive flight pattern is easy to spot.
In reply to OP:
A solo treker can do a lot out there. Lots of good walks out there and huts that you can stay at. Sadly though, its not a cheap place at all!
From Nanortalik, there's a good ferry service (however, there is talk of this being replaced with a helicopter service) that will take you all over the place. It's also perfectly possible to hire local boats to ferry you over shorter distances.
BTW, Niels at the tourist office in Nanortalik is very very helpful.