...and the species is rostrata, as labeled by Chen Young under the same photo on this page from the Crane Flies of Pennsylvania site.
Image moved to new Guide page, but since subgenus is not available as an option when creating pages, I had to use "No Taxon" for the subgenus Geranomyia.

Thanks, Paul. I'm not sure what type of flower this is, but it definitely attracted a lot of these crane flies as well as other dipterans. I guess food sources are getting a bit scarce as the weather is becoming colder.

Well, the North American flora is hughly differetn from the European but it is clear that it is a composite flower (Compositae or Asteraceae), possibly genus Aster (difficult to see on such close-up). The flowers in the middle are probably narrow and deep and nectar maybe difficult to obtain for any insect that has not a long proboscis or not enough power to force its proboscis in. Most will go for pollen.

Of course, later in te year, any patch with flowering plants will attract many insect. When the sun is shining, here places with Aster will give good results for collecting, but the best usually is ivy (Hedera) in flower in a sunny place. No luck now, though, when it is close to freezing.

Paul

http://www.diptera.info