Ask A Scientist© Biology Archive

name         ALAN
status       other
age          40s

Question -   WE BOUGHT A NEW (PREVIOUSLY OCCUPIED) HOME IN WESTERN
PENNSYLVANIA.  HOME IS PLAGUED BY WHAT APPEAR TO BE SMALL HOUSEFLIES.
THESE LOOK LIKE BABY HOUSEFLIES THAT NEVER MATURE.  THEY ARE BLACK ONLY, NO
COLORATION, NO IRRIDESCENCE.  THEY ARE NON-AGGRESSIVE AND VERY EASY TO
KILL--THEY JUST SIT ON THE WALL WAITING TO BE WHACKED!  PREVIOUS OWNER OF
THE HOME HAD SEVERAL DOGS AND CATS THAT SPENT A LOT OF TIME IN THE HOUSE.
THEY SEEM TO APPEAR LATER IN THE EVENING AND AT NIGHT--PERHAPS DRAWN BY
LIGHTS.  DO YOU HAVE ANY IDEA (1)WHAT THESE FLIES MIGHT BE? (2)WHERE ARE
THEY COMING FROM?  THERE IS NO FOOD SOURCE, NO ANIMALS IN THE HOUSE NOW,
NONE OF THE USUAL THINGS THAT WOULD DRAW FLIES.  THANKS!

Most likely fruit flies, very common mid to late summer in houses,
especially where fruit has been left exposed.
J. Elliott


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It may be "Black Flies", these are common with house plants and will thrive with 
mold infestations especailly around bathrooms.  Try fly paper around the area 
they are mostly seen.

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