As a followup to the images referenced below, I saw this cooperative conopid today, again feeding on Oxeye Daisy.
The first photo shows the wing veins (left, undamaged wing) and the antennae.
The second photo shows the proboscis in feeding position--note the hinge.
The third photo shows the proboscis in rest position. (Think Groucho Marx.)
The fingernail is 10 mm in length.
The fourth photo is merely a crop of the wing.

For comparison, see this page with another conopid, with a double-hinged proboscis.

Earlier submission of probably the same species, in the same location: