# Housefly size **URL:** \ **Category:** Factual Questions\ **Created:** [March 30, 2009, 1:44am UTC](https://boards.straightdope.com/t/housefly-size/491246 "2009-03-30T01:44:33Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Pseudocode](https://avatars.discourse-cdn.com/v4/letter/p/59ef9b/32.png) [@Pseudocode](https://boards.straightdope.com/u/Pseudocode)\ **Post date:** [March 30, 2009, 1:44am UTC](https://boards.straightdope.com/t/housefly-size/491246/1 "2009-03-30T01:44:33Z")
I had a few flies in my apartment, so I decided to attempt to identify them. After doing some research, I think they look like common houseflies (Musca domestica). However, they are certainly larger (25 mm) than my research is telling me to expect (6-13 mm). They are very easy to catch because they don’t move when you get close to them (unlike the smaller houseflies I am more familiar with). So are they just large houseflies, or do I have a different species? ---
**Author:** ![Beware\_of\_Doug](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@Beware\_of\_Doug](https://boards.straightdope.com/u/Beware_of_Doug)\ **Post date:** [March 30, 2009, 2:58am UTC](https://boards.straightdope.com/t/housefly-size/491246/2 "2009-03-30T02:58:15Z")
Maybe what you have are _horse_flies? ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [March 30, 2009, 3:06am UTC](https://boards.straightdope.com/t/housefly-size/491246/3 "2009-03-30T03:06:22Z")
Possibly [cluster flies](http://www.drbug.ca/cluster_flies.php). These are the ones that seem to materialize from nowhere on the windows. ---
**Author:** ![Pseudocode](https://avatars.discourse-cdn.com/v4/letter/p/59ef9b/32.png) [@Pseudocode](https://boards.straightdope.com/u/Pseudocode)\ **Post date:** [March 30, 2009, 10:16pm UTC](https://boards.straightdope.com/t/housefly-size/491246/4 "2009-03-30T22:16:29Z")
No, it did not look like either of those. It looked exactly like [this](http://www.flycontrol.novartis.co.uk/species/housefly/en/adult.shtml). It was much bigger housefly than I’ve ever seen. I guess I’m just surprised that they could get that big. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 31, 2009, 1:07am UTC](https://boards.straightdope.com/t/housefly-size/491246/5 "2009-03-31T01:07:33Z")
Wait, 25 mm? As in, an inch long? I’ve never seen nor heard of a dipterid that size. And I’m very glad to have never seen one. ---
**Author:** ![horsetech](https://avatars.discourse-cdn.com/v4/letter/h/dec6dc/32.png) [@horsetech](https://boards.straightdope.com/u/horsetech)\ **Post date:** [March 31, 2009, 2:34am UTC](https://boards.straightdope.com/t/housefly-size/491246/6 "2009-03-31T02:34:24Z")
You are very lucky, indeed, Chronos. Tabanus spp. horseflies are big mothersuckers. I have been pursued by a horsefly that kept up with me and the horse at a brisk trot (on a big horse!) and did not fall back until the horse started cantering. We call them B-52’s because they sound like droning airplanes as they cruise around looking for fresh blood. They’re a bit like a cross between a bumblebee and a vampire. Here are a couple photos – DO NOT LOOK if you are squeamish – BUG PHOTOS, YOU HAVE BEEN WARNED: [http://images.whatsthatbug.com/wp-content/uploads/2009/01/horse\_fly\_scaptia\_lata\_argentina.jpg](http://images.whatsthatbug.com/wp-content/uploads/2009/01/horse_fly_scaptia_lata_argentina.jpg) [http://img2.travelblog.org/Photos/1434/3404/t/11057-Patagonian-Horse-Fly-0.jpg](http://img2.travelblog.org/Photos/1434/3404/t/11057-Patagonian-Horse-Fly-0.jpg) There, did the hair on the back of your neck stand up? Mine sure did. Sorry I can’t help with the OP. ---
**Author:** ![Ruby](https://avatars.discourse-cdn.com/v4/letter/r/13edae/32.png) [@Ruby](https://boards.straightdope.com/u/Ruby)\ **Post date:** [March 31, 2009, 3:27am UTC](https://boards.straightdope.com/t/housefly-size/491246/7 "2009-03-31T03:27:51Z")
We have horseflies and they can indeed get an inch or so long. And they bite like a mofo. We also have the large flies that I think the OP is referring to. We find them in the early spring and they look just like an overgrown house fly. They are easy to kill as they move slow. I’ve always assumed they were indeed houseflies that have “overwintered” in the house either dormant or minimally active. In my theory, they lay eggs and then die a normal housefly lifecycle death which explains why we don’t see them the rest of the year. Sorry I couldn’t be of more help.