If you go with the scented geraniums, be aware there are lots of difference scents, make sure you get a citronella one, it should smell lemony.
How about one of those "bug zappers", hang it over the run and take the bottom off so the flock can enjoy some barbecued bugs! IDK if they are effective for mosquitoes, or just moths, but entertaining nonetheless.
If you want to really do bug control right, build a bat house and see if you can get a colony of bats close by. They are they world's most effective biological control of night flying insects, and they are in decline in many places, so you'd be doing good all around. This is a bit more "long term", of course.