---

I found last summer this specimens of Chrysotoxum elegans(hope it is the right ID). when I collected and I saw those aberrations I thought the pollution had a strong impact on them. My first thought was the pollution because near the collecting site (Iron Gates Natural Park, Sirinia Valley) in the recent past was a coal exploitation. What is your ideas?

---

As far as I am aware these aberrations might also be cause by 'damage' on the puparium, like a bump during pupal stage or some continuous pressure.

---

this one has an aberration which looks like a scutellum

---

and a last one..

---

Thank you Paul for your answer. That it is an idea that I didnt't take in account. now when I am thinking i realize that it might be a possibility.
Maybe somebody else has another ideas...

---

I suspect that they may be caused by parasitoids - only in these cases the host 'wins' and manages to kill the parasite larva before it causes too much damage. I have no real evidence for the hypothesis, but it is probably significant that this type of aberrantions in rather common in Syrphinae which predatory larvae, but less so in other flies with less accessible larval stages.

---

Did you only find this in C. elegans?
If it's pollution, you would expect abberations on other parts of the body as well. Head, legs, wings... etcetera. More likely Paul's idea comes closer. Perhaps it can have it's ground in the places where they hatch from pupa to adult stage. Not only inside the cocoon, but also in the vulnerable moments as 'fresh-and-soft' adults right after hatching. Try to find the larvae/pupa ;)
It's certainly odd... for sure, especially picture 2...

---

Thank you...I will search more next year and yes from this area I have only C. elegans with this kind of abberations (and I have some other Chrysotoxum sp. from that site)...
Amalia