Fly problem

Jen Matthews jmatthews at
Wed Jul 2 10:57:48 EST 2003

Hi Maggie,

Is your problem with the common house fly (Musca domestica) or with 
one of the many aquatic or semiaquatic species of flies. If you can 
identify the type of fly you are dealing with, you may be able to better 
direct your control efforts. One common fly species found near aquatic 
environments is the moth fly or drain fly. I've included some information 
below. good luck, -Jen  

Moth Flies Moth flies (Subfamily Psychdidae) have many names 
including drain flies, filter flies and sewage flies. The widespread 
subfamily Psychdidae contains four genera with over 50 aquatic and 
semiaquatic species in North America. Adults range in size from 1.6 =96 
6.4 mm. They may be yellow to brown to black in color. The adults are 
hairy and hold their wings roof-like over their bodies when resting. 
During daylight, they will often be found resting on walls near drains. 
They are most active during the evening and may be attracted to light. 
Moth flies do not bite.  

Moth fly larvae are rarely seen because they live in drain areas or other 
protected locations. Most larvae are cylindrical or slightly flattened and=
are usually less than 5 mm in length. The larvae entirely lack prolegs 
and body segments are usually subdivided into annuli. The thorax is 
not distinctly thicker than rest of body. They often have a pale 
underside with a darker head and tail, and dark bands (dorsal plates) 
across their backs.  

Both larvae and adult forms feed on microorganisms, fine detritus and 
other decaying material. Adult female moth flies most often lay their 
eggs in masses on the surface of gelatinous films found in drains and 
sewers or other dark, moist areas. Adults live about two weeks. Moth 
flies are not strong fliers and cannot fly long distances. Most 
infestations originate in the area where the adults are found. Any 
aerosol or spray insecticide will easily kill the adults but these are not=
recommended in aquaculture facilities. For effective and long-term 
control, the breeding sites must be found and removed. Inspect drains 
and other moist areas for potential breeding sites. Drains can often be 
cleaned with over-the-counter cleaners or diluted bleach followed by a 
hot water rinse. If this is not successful, mechanical cleaning with a sti=
brush may be required to remove any film lining the drain.  

Jennifer L. Matthews, DVM, PhD
Zebrafish International Resource Center
5274 University of Oregon
Eugene, OR 97403-5274     <(()><
(541) 346-6028 ext. 14             <(()><
Fax (541) 346-6151
jmatthews at

On Tuesday, July 1, 2003, at 12:02  PM, Mctighe, Maggie S wrote:

> One of our investigators has a large room with 10 racks of zebra
> fish. The racks are 5 years old and are marine biotech shelf
> overflow design. He has bug zappers in the room, and the room is in
> a university basement.  There are no open windows anywhere, but we
> have a fly problem.  Need suggestions for getting rid of flies. 
> Thanks!

More information about the Zbrafish mailing list