Reptile & Amphibian Forums

Hello everyone
I wonder if someone is able to answer the following? I always thought that flies (house, France)laid eggs. But recently I swatted a fly and as I was picking it up I noticed 10 or so maggots around it.

Yesterday I found a dead fly on my kitchen floor & decided to put it in a plastic bottle - there was no evidence of maggots. Today the bottle is full of maggots!

Question is - are the maggots alive inside the flies or do flies keep eggs inside them rather than finding somewhere to lay them?

I would be really grateful to know the answer! Thank you in advance!

Maggots would typically originate from the fly (that was swatted). The eggs will hatch at an accelerated rate as the chemical decomposition of the female fly is detected; thus, feeding on the female fly's body. This is an evolutionary adaptation for keeping the species alive in negative circumstances.

There are some cases where one fly species will parasitize another species with eggs hatching on the victim & consuming that fly alive. There are other cases where eggs are laid on a fly by another species, and the maggots get a "free ride" to their new source of food.

Thank you so much for your reply - I am finding this fascinating! Would you mind answering the following?

In scenario 1 you say that the Maggots would typically originate from the fly (that was swatted) & the eggs will hatch at an accelerated rate as the chemical decomposition of the female fly is detected - Does this mean that flies do lay eggs but they are not always laid immediately that they are formed - hence there can be eggs inside the fly waiting to be laid?

There are some cases where one fly species will parasitize another species with eggs hatching on the victim & consuming that fly alive - Given that immediately I had swatted the fly I could see the maggots this sounds like the answer in this case - would the maggots (having hatched) buried themselves inside the victim & be feeding from the inside?

Thank you so much!

In scenario 1 you say that the Maggots would typically originate from the fly (that was swatted) & the eggs will hatch at an accelerated rate as the chemical decomposition of the female fly is detected - Does this mean that flies do lay eggs but they are not always laid immediately that they are formed - hence there can be eggs inside the fly waiting to be laid?

Yes

There are some cases where one fly species will parasitize another species with eggs hatching on the victim & consuming that fly alive - Given that immediately I had swatted the fly I could see the maggots this sounds like the answer in this case - would the maggots (having hatched) buried themselves inside the victim & be feeding from the inside?

In this scenario where you saw maggots right away -does not necessarily mean that the fly was parasitized; again, some flies may have eggs hatch within minutes. The type of fly(I forgot the name) that parasitizes other flies with their eggs which hatch onto the victim, lives in south America.

Thank you Lizardman!