I live in Taipei, and these flying insects are about 2-4 millimeters long (body length). They are very active when it's over roughly 24C indoors, and will fly, land and run around randomly on interesting surfaces then fly again, all in one continuous motion.

Some have moved into my apartment again.

They are attracted to food, especially coffee grounds!, vinegar, bread, and dark, moist areas. I can use these attractants to catch them inside bottles or plastic bags, but can't ever seem to get the last one.

I see them fly around while mating end-to-end (twice as long as a single fly) and they often go right past my face while doing so as if to say "ha! there's more of us on the way!"

The heads seem smaller than in images of common fruit flies that I've seen.

Are these likely to be fruit flies, or something else? I don't need an exact species identification, I'd just like have some kind of classification to describe them with besides "little flies".

In this answer to a related but different question, it was proposed that they were something very different, but I don't think that's the case.

Photos: the best I cold do with my cell phone plus a magnifying lens.

enter image description here

  • $\begingroup$ Didn't the last answer say it was a baby cockroach $\endgroup$ Feb 20, 2019 at 7:39
  • $\begingroup$ @SonicSplasher That was an answer to a question about pesticides, not a species identification question, so even though it was suggested, I'm pretty sure these are not baby cockroaches. See my comment there. I can't help it that that answer's formatting makes it look like it's answering a species id question. $\endgroup$
    – uhoh
    Feb 20, 2019 at 7:47
  • $\begingroup$ Search for drosophila buzzati and drosophila buskcii and drosophila simulans $\endgroup$ Feb 20, 2019 at 8:00
  • 1
    $\begingroup$ This has been recently bumped by community; I add this comment for closure. This is a six-legged (hexapod) two winged (dipteran) fly. It is a female drosophilid, and identifying the species and subspecies from such a photo is impossible; typically, correct identification requires careful morphological assessment using a microscope, by a specialist/insect taxonomist. I don't think this fly is shaped like a Drosophilia melanogaster member. It seems a bit too long. Source: personal daily experience with manipulating fruit flies on a CO2 pad. $\endgroup$
    – S Pr
    Nov 18, 2019 at 9:14
  • $\begingroup$ @SPr Thanks for your comment! The "ultimate closure" in Stack Exchange is of course acceptance. If you'd consider writing up something along the lines of "...without the possibility of genetic analysis... correct identification requires careful morphological assessment using a microscope, by a specialist/insect taxonomist." I could probably accept it. $\endgroup$
    – uhoh
    Nov 18, 2019 at 9:49

1 Answer 1


Commom fruit fly
I can't pinpoint on the species name but a quick common fruit fly should give you a image which look very similar to the one in your photos.

  • these Bois are around 1/8 in inches long -striated abdomen

Hope this is the one

  • $\begingroup$ I mentioned that, but: "The heads seem smaller than in images of common fruit flies that I've seen." Your guys have a big head with a tiny neck, my guys seem to have a "unibody" $\endgroup$
    – uhoh
    Feb 20, 2019 at 8:02
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    $\begingroup$ The thing is baby roaches cannot fly and the ones you mentioned are flying so this is the most similar one I can come up with or maybe some sort of Taipei variant $\endgroup$ Feb 20, 2019 at 8:04
  • $\begingroup$ Thanks, I didn't think they did, I'm glad to know for sure now. I really appreciate the confirmation on the "no fly" baby roaches. $\endgroup$
    – uhoh
    Feb 20, 2019 at 8:09
  • $\begingroup$ What kind of insect is a Bois? $\endgroup$
    – David
    Jul 21, 2019 at 19:44
  • $\begingroup$ "bois" here was another word for boys and i used boys informally to you know call them that without addressing them with their scientific name $\endgroup$ Feb 8, 2020 at 18:56

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