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Old 09-24-2020, 11:37 AM   #4
TexasBryan
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City: Clear Lake Shores
Vessel Name: Pegasus
Vessel Model: 52 Prima Seahorse
Join Date: Sep 2019
Posts: 45
Drain flies are bigger than fruit flies and have black wings. When you smash them on the wall, you'll see that they leave a black smudge.

Drain flies depend on the organic material that builds up in drains/tanks to live and breed. Drains are the most common source, but also inspect your holding head/tank just in case.

A couple of ideas to track down the source, or sources; Smear a little Vaseline inside solo cups and place them upside down over the drains, or, seal drains with clear tape, sticky side down, poke a few air holes so they still try to exit. Leave the traps set overnight (or longer) as they are more active at night. When you identify the source drains, you are on the hunt!

Drain flies have a fairly long life cycle of 1-3 weeks, so you need to wipe out the egg cycle (~48 hrs), larvae stage (~12-14 days) and breeding adults all at the same time to be fully rid of them.

Clean the suspect drains with your drain cleaner of choice. Bleach may kill the larvae on contact, but if the food source remains, you are still subject to new outbreaks if you still have adult flies around. Once the drains are cleaned, I suggest keeping a cup over the drain opening whenever the drain is not in use for several weeks until the life-cycle is broken and you don't see any more flies.

Good luck!
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