Subject: Bristle fly
Location: Mokotua, near Invercargill, NZ
April 23, 2013 1:35 am
Hi there. This photo was taken in the autumn here, late in the day. The fly is on a Juncus rush, near a wetland area, with lots of native vegetation dominated by manuka. Hope the photo is clear enough.
Signature: Gay

Possibly Tachinid Fly

Dear Gay,
We believe this is a Tachinid Fly in the family Tachinidae.  See BugGuide for additional information.  The larvae of Tachinid Flies are internal parasites that kill their insect and arachnid hosts.  Generally each species of Tachinid Fly is very host specific, so they are important biological control agents.

Hi Danial.
Thanks very much for that information. Confirms what our local bugman suggested, but interesting to hear that these flies are host specific and potentially a part of controlling pest species. Your time on this one is much appreciated. That’s an excellent website and resource you have there.
Cheers, Gay

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Subject: help me identify this fly
Location: Baie-Comeau,Quebec,Canada
September 10, 2012 2:48 pm
I found this fly in front of my house.I live in Quebec,Canada.In a small town called Baie-Comeau.I’ve never seen such fly arround here and no one I know either…It was half inches long and about same wide with the wings.
wSignature: Pierre Murray

Tachinid Fly

Hi Pierre,
This distinctive fly is a Tachinid Fly, and we believe the species is Hystricia abrupta based on images posted to BugGuide.  The range is also consistent with your sighting.  Tachinid Flies are important parasites that prey upon a variety of insects and arthropods.  According to BugGuide:  “Larval stages are parasitoids of other arthropods; hosts include members of 11 insect orders, centipedes, spiders, and scorpions. Some tachinids are very host-specific, others parasitize a wide variety of hosts. The most common hosts are caterpillars. Most tachinids deposit their eggs directly on the body of their host, and it is not uncommon to see caterpillars with several tachinid eggs on them. Upon hatching the larva usually burrows into its host and feeds internally. Full-grown larva leaves the host and pupates nearby. Some tachinids lay their eggs on foliage; the larvae are flattened and are called planidia; they remain on the foliage until they find a suitable host.”

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Hello again, Daniel.
Apologies for two messages in one day, but our earlier correspondence reminded me of something.  Back on June 25th I sent you a couple of photos of a questionmark  caterpillar that I’d mentioned had later been parasitized by a tachinid fly, which was also raising havoc with my monarch caterpillars.  In answer to your request, I had to say I hadn’t photographed the fly.
Anyway, since then, I’ve kept several of the little maggoty buggers in a medicine bottle, allowed a few to emerge, and then put them in the freezer.  I remembered today, after another monarch was killed.  Here’s a mug shot.  The “pills” are their pupal cases.  I don’t know the species, and I don’t care!
Like so many of these flies, they emerge when the caterpillar is in the process of going into it’s pupal stage, or sometimes even after the chysalis is formed.  Then the maggot comes out, and rappels to the ground on a long filament, and upon finding a spot to it’s liking, becomes a pupa itself.
I understand these amazing creatures role in the natural world.  I’ve read alot about their incredible lifecycle.  But I love moths and butterflies more, and these little monsters seem to take perverse pleasure in killing my favorites right at their peak, after they’ve gone through their entire laval stage.  I hate them!
Anyway . . .
Cheers, and thanks very much for all you do.
Don J. Dinndorf
St. Augusta (central), Minnesota

Tachinid Flies and Pupae

Hi Don,
Thank you for providing such an educational posting on the life cycle of Tachinid Flies for our readership.

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Subject: What is the name of this fly?
Location: Catalina Island
August 4, 2012 2:08 am
I saw this interesting fly on a plant on the Wrigley Botanical Garden and could not find it listed in any Catalina Island guidebook. I believe the order is Diptera. Can you identify the family, genus and species, please?
Signature: Rosemarie

Spiny Tachinid Fly

Hi Rosemarie,
This is one of the Tachinid Flies in the family Tachinidae.  Tachinid Flies are a diverse family, and according to Charles Hogue in Insects of the Los Angeles Basin:  “Most species of this group resemble overgrown House Flies but are covered with extra-heavy stiff bristles.  The thorax is usually a solid color and is not banded lengthwise as it is in other domestic flies.  Tachinid Flies are often seen flying closely over or crawling through low vegetation in search of insect larvae (cutworms and the like) upon which to lay their eggs.  The larvae are parasitoids that feed internally on the host; as the hosts are caterpillars, including cutworms and loopers, Tachinid Flies are considered beneficial to the gardener and farmer.”  We believe this is the Spiny Tachina Fly, Paradejeania rutilioides, based on images posted to BugGuide and the range which is the southwest portion of North America.  Often island populations evolve into distinct subspecies and we are not certain if this is the case with the Santa Catalina Island population.  BugGuide lists the host as the larvae of Edwards’ Glassy-Wing, a species of Tiger Moth that feeds on oak in its larval stage.

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Subject: Robber Fly?
Location: Baldwin Hills in Los Angeles, CA
July 20, 2012 11:56 am
Hi Bugman,
Found this guy last week on a backyard window sill. S/he seemed a bit worn down. I’d guess length to be 3/4”.
I’ve pics of a larger yellow/black robber fly in the same area from last year, if you’re interested.
This brown one is smaller but reminiscent of other robber flies I’ve seen on your site.
Thanks for all your great work and insights.
Signature: Tracy

Tachinid Fly

Hi Tracy,
This is not a Horse Fly.  It is a Tachinid Fly, a member of a family of flies that parasitize other insects and arthropods.  This is a large, diverse and confusing family, and we did not know if we would have much luck with a genus or species identity, but the white face seems rather distinctive.  Upon doing a web search, we found this very similar photo on Bugguide, and we suspect your fly is probably in the same genus, Gonia.  BugGuide has this photo of a genus member from California.

Tachinid Fly

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Subject: flies? bees?
Location: central Wisconsin
July 11, 2012 8:39 pm
At first I thought they were bees, many of them going from flower to flower. But faster, and more skittish. They look like flies, but what flies go to flowers?
Signature: mkeen3

Tachinid Fly

Dear mkeen3,
This is a Tachinid Fly, but we cannot be certain of the species because it is a very large family and many members of the family look similar.  Your individual looks very much like this Tachinid Fly image we posted earlier in the week.  Tachinid Flies are very important components in the food chain.  They are parasitic flies that often target a single host in the insect and arthropod world.  Many Tachinid Flies prey upon caterpillars and true bugs.  It is the larva that is the carnivore and the female Tachinid Fly lays an egg on the host creature.  The egg hatches and the larva begins to feed on the internal tissues of the host, eating it alive, eventually killing it.  Many adult Tachinid Flies are pollinators that feed on nectar and pollen from blossoms, but Tachinid Flies are not the only Flies that go to flowers.  Bee Flies, Hover Flies and Small Headed Flies are just a few of the families of flies that are important pollinators.  You may have heard the old saying “You can attract more flies with honey than with vinegar” though sometimes “vinegar” is replaced with the more colorful slang term for excrement.  Honey is nothing but the nectar of flowers that is gathered by bees.  So to answer your question, many flies go to flowers.

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