Unusual parasite problem

[mcheki]

I am based in England and over the years have received many parcels containing papered butterflies direct from several countries in Africa. Never before have I opened a paper triangle and found a large number of (very small and very dead) hatched pupae and adults with wings beside the butterfly specimen. Yes, of course, occasionally there are signs and indications of dermested and beetle damage and occasionally dead specimens of these are found. This finding suggests a parasite that was living on or in the adult butterfly at the time of death. Pupae of parasitic wasps are more associated with the caterpillar stage with these parasites emerging either from the dead caterpillar or later emerging from the butterfly/ moth pupa. This is well documented. Has anyone else experienced this finding? This photo shows the parasite in situ.

I have almost no knowledge of flies and wasps and was hoping someone can make a determination from this close up picture of the pupae and adults as they were found in the paper triangle. The specimen originated in Uganda and came from a very reputable source. It was one of several hundred specimens and no others were affected. As far as I can see there does not appear to be any exit hole(s) in the butterfly, but further checking is in progress.

[Adam Cotton]

These are not parasites, but flies of the family Phoridae which laid eggs in the dead specimen before it was dry and the larvae then ate the body and pupated in the envelope. In nature some species of Phorid flies are part of the decomposition process of dead insects and animals, but others feed on decaying vegetation or on fungus.

Phorids are quite easy to recognise because they look like 'hump-backed' fruit flies, and interestingly the live flies like to run.

Adam.

[mcheki]

Thank you, Adam. A very interesting reply and one that had not crossed my mind. This explains the powerful looking hind legs. I will add that I set the specimen yesterday and had no problem doing so. There was no indication of damage so I assume that the damage is all internal and the exoskeleton has survived intact.
This is what I like about ICF in that one can always learn more about insects from fellow enthusiasts. If you don't know something and ask then usually someone can help and solve the query.