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Hi,

I'm knew to all this, hopefully I am not wasting anyones time on this, but would like some help identifying this fly. We live in Wellington New Zealand and have just noticed these flies appearing on our deck in large groups (around 10 to 15 flies in some instances). They are very large (roughly twice the size of standard house fly) and are freaking my wife and daughter out. Would love to know more about them if possible.

Thanks

Sandy Leadbeater

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Hi Sandy,

Gerard and I had a look at the pictures and we agreed that it should be a tachinid fly. Digging into some books did not change our opinion. The flies resemble the subfamily Tachininae but we are by no means experts in this family.
Tachinids mostly parasitise on caterpillars, but some on true bugs, leatherjackets, beetles larvae or other arthropds. So there is no way they can be harmful to your family, other than that they are 'scary'. Perhaps you had a 'plague' of moths recently?

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That is one beautiful fly! You should be proud to host their parties. ;)

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Dear Sandy,

It is a Tachinid fly already, and a very beautiful one !
It is completely harmless (at least, to humans, not to caterpillars)
It looks indeed like member of the tribe Tachinini.

Maybe a difficult request, considering you are at the other side of the world, but,
if you could collect one and send it over to me, I could try identifying it.

My emailaddress reads th.zeegers@tref.nl


Theo

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I have caught a number of flies like this and believe the genus to be Protohystricia. There are five species listed on the New Zealand checklist. It may be P. alcis