Earlier this week we were called to an area of the base on Pearl City peninsula to check to check out a fly problem. Evidently the problem has been persisting for some time, and the pest control shop called us in for a consult. We collected some specimens and it turns out they have two fly problems which appear to be unrelated – infestations of phorids and psychodids. We collected a lot of psychodids (Diptera: Psychodidae – drain flies or moth flies) from the shower, but other work spaces were infested with phorids (Diptera: Phoridae).
It seems pretty clear that the flies in the shower are breeding in the drain area. There was a long drain that spanned the length of the shower and was harboring a lot of scum. I was a little surprised though at how tiny the psychodids were – I am more used to seeing the larger blackish gray species. These were very tiny. One of the pictures below (sorry about the poor quality – I used my point-and-shoot through the miscroscope lens) was taken on a dime, just above the date, for scale. This should be a pretty easy fix. We’ll put together some options for them on what they can use to clean the drain and prevent the flies from breeding there.
The phorids may be a different story. Below is a picture of a fly tape they had hanging in an office area – as you can see, it was covered with the flies. There were two separate buildings on the compound, and they both are having problems with the phorids. This leads me to believe that there may be an outside area where they’re breeding. There was a recent mangrove removal project on Pearl City peninsula in which they basically mulched the mangrove into large piles on the shore line. The mangrove mulch is not far from this particular compound, so I am curious if this is the source of the phorids. We need to go back and check this out.