Posted by mtarini on 10-08-2008 23:40
#1
I hope someone can solve this mystery for me.
Sorry, I took no picture.
Short story: I squashed a big, green-colored fly, and it turned out that inside it was literally packed with dozens and dozens of tiny and very alive white worms.
What can they be?
- Internal parasites infesting the fly? (how could it be alive? they were literally covering most of its volume)
- Offspring of the fly, as if its eggs hatched inside? Is it possible?
Details:
- I live in central Italy. Happened a week ago, in a very hot August night.
- The fly looked like a large common house fly, maybe 2.5cm in length, but it was green with red eyes. From the gallery, I see it could be maybe a female of
Protocalliphora azurea http://www.dipter...to_id=1616
or something similar.
- The fly was totally alive before being smashed (sorry about killing it, I just couldn't sleep). I've seen it around in the house two days before that night.
- The worms looked just like very tiny maggots, all white with a dark tiny head. They were maybe 2 mm in length each. I've seen maybe 20 alive of them. They didn't do much except slowly moving over each other. They seemingly occupied most of the now broken exoskeleton of the fly, not only the abdomen but the torso too.
I've searched the web and the forum here but it can't find anything relevant so I'm just terribly curious.
Thanks in advance!
Edited by mtarini on 11-08-2008 00:29
Posted by Paul Beuk on 11-08-2008 07:05
#2
Well, some flies are not oviparous (laying eggs) but larviparous (laying larvae). Basically this means that the eggs hatch inside the female abdomen before oviposition takes place. If you were to squash such a fly which is about to 'give birth' you will get what you got. So the worms did not only look like tiny maggots: they were!
Posted by mtarini on 11-08-2008 19:29
#3
Thank you Paul Beuk!
I didn't know that, and thanks to you I have a perfectly good explanation for what I've seen!
Great forums BTW.
Posted by Nosferatumyia on 11-08-2008 22:29
#4
It happens not only in the case of calyptrates, but also in a few parasitic acalyptrates, namely in the circumtropical family Ctenostylidae; they have lost the piercing ovipositor present in related Pyrgotidae, but are ovilarviparous instead; eggs can be inserted like the egg of Stylops, with its beardy, sclerotized and acute egg, which contains the 1st instar larva in. Matsumurania (Tephritidae) is also larviparous, but its larval feeding habits are unknown.
Posted by Kahis on 12-08-2008 08:57
#5
This sort of development is rather widespread in Diptera. At least 22 families have members that larviposit or lay fully developed eggs with a larva inside. It is found also among the 'lower Brachycera' like Ocydromia in Hybotidae (Empidoidea).
Meier et al. have written a review of the topic: RUDOLF MEIER, MARION KOTRBA and PAUL FERRAR (1999). Ovoviviparity and viviparity in the Diptera. Biological Reviews, 74, pp 199-258