#1
On several locations I have found this Hydrellia pupa which differ from many other species of Hydrellia by its black dorsal markings and, what appears to be, anterior spiracles. The constricted abdominal segments show an extra smaller ring in the intersegmental furrow, which I have never seen in other Hydrellia. Can these combination of characters be attributed to a specific species? As in other Hydrellia (and Notiphila) the anal segments shows 2 (curved) spines, but unlike Notiphila the cephalopharyngeal skeleton is more simply built. I'm not sure if these paired black spines on the head are indeed anterior spiracles, for these are normally absent in Hydrellia larvae. However, in many diptera larvae, which normally have no anterior spiracles, they may develop when the larva pupates.
Pupa are found early september.
#2
Looking at your photos, I wonder whether this is a parasitised
Hydrellia pupa, the parasitoid causing some problems, such as non-absorption of the larval antennae (which seem to me to be too far forward for anterior spiracles).